Finish what you start!

I don’t know when I picked up on this idea. It might have been while doing crafts as a child. Maybe it happened while working on school assignments. It could also have occurred while learning to play an instrument or doing sports. I do know this. I have absorbed the idea that I must finish what I start—and I have disciplined myself with it for decades.

I have been told that children need boundaries as they grow up. I suppose they also need to be taught perseverance and discipline. Admittedly, these traits can go a long way. From my pre-university education, they first led me to a master’s degree and then to a PhD. However, once discipline blends with a sense of obligation, an exhausting dynamic arises.

During each phase of my life, I’ve taken up new hobbies and activities. I thoroughly enjoyed them, but I’ve always had a hard time moving on. For example, I took piano lessons until I went to university. While spending time studying and building a new life, I swayed between wanting and feeling obliged to continue my hobby.

Many years later, I looked back at the research projects I worked on during my PhD. Were they done once I obtained my doctorate? Not in my mind. Despite transitioning to a job in industry, I still wanted to continue these projects. Similarly, I’ve spent countless hours computer programming. I have published some of the resulting software. Nonetheless, most projects never went beyond ideation or being a useful tool for me. They’re still lingering in my mind, though.

Life goes on. One life phase succeeds another. Activities come and activities go. But I’m still clinging to them. My discipline still wants me to improve my long-gone skills. I keep feeling obliged to bring my past projects to some dreamed-of endpoint. But I can’t. I don’t have the time. I don’t have enough energy. My list of goals is exhausting me and taking away my joy.

It’s time to get real. I began pursuing other interests. I’ve steered my career in a different direction. I’m focusing on new projects. For all practical purposes, I’ve left behind most of my ideas, plans, and projects. But I still need to break through my sense of obligation toward my past pursuits, consciously say goodbye to my goals, and strike them off my mental to-do list. That’s what I’ll attempt to do here.

Personal

Playing the piano

I took piano lessons from when I was about eight years old until I left secondary school. I wouldn’t say I was particularly talented, but after a decade of practicing, I was playing Mozart’s sonatas. When I went to university, I had neither a piano nor a keyboard at hand. Practicing at most once every few weeks, I quickly had trouble keeping up my musical skills.

A few years later, I had more regular access to a piano for a while. Sometimes, I’d practice my dexterity. I mostly tended to pieces I once liked a lot and could still play relatively easily, though. As time passed, I could still play these pieces by muscle memory, but I couldn’t read the sheet music at my playing speed anymore. My ability to play the piano had clearly begun to deteriorate.

I thought it was a shame to lose my skills and felt I should have kept practicing my hobby all along. Spending my time on other activities, I never truly invested in playing the piano again, though. My deficit approach wasn’t inviting me to do so either. I mostly saw that I wasn’t playing as well anymore. Focusing on what I hadn’t learned, like sight-reading or improvizing, I also lacked the confidence to play with others.

I haven’t seriously played the piano in years. My skills have eroded to the point where I’d need serious practice to get back into it. I might do so someday. Yet, any renewed interest in playing the piano would have to come from playfulness and joy. Otherwise, I’d only be compensating for what I’ve lost. At the moment, I don’t see any potential joy overcoming my compensation drive. Besides, I’m investing my time in other activities. So, I’ll let my electric piano sit decoratively in the corner of my living room for now.

Dancing

While I was growing up, a skatepark opened in my hometown. As I had inline skates and the park was close to my home, I often visited it. I wasn’t a very courageous boy, though. I once tried to roll down a ramp, fell hard, and never tried again. Still, I thought it was cool to watch the skaters and BMX riders show off their tricks.

Once, during a special event, there were breakdancers at the skatepark as well. Shy as I was, my stepmother encouraged me to take a look, and I was instantly captivated. While we were watching the b-girls and b-boys perform, a man came up to us and invited me to a trial class. I wasn’t able to attend the first session, but I kept going afterward.

We were training at a local youth center when smoking was still allowed in some public buildings. I hated coming home smelling of cigarettes, but learning to b-boy felt really cool. However, after about a year, we moved to another town where I couldn’t continue taking breakdance classes.

Four years later, I moved to the university city of Groningen. After trying out a fraternity-style rowing club—which wasn’t my thing at all—I discovered the city’s vibrant hip-hop scene. Before long, I also found the dance school next to the city’s central square that was offering breakdance classes. I kept training there throughout my studies. In my prime, I’d practice two to three times a week. Those were arguably the fittest years of my life.

After returning to Groningen for my PhD, I picked up breakdancing again, but I wasn’t as enthusiastic about it as before. The dance school had moved from its prime location to the back room of a gym and limited the training hours. Many of the people I had previously met, including my teachers, had left. When a few colleagues introduced me to dancing salsa, I happily traded one breakdance session a week for a salsa class.

With only one regular session remaining, I could maintain neither my physique nor my breakdance moves. Besides, breakdancing had always been hard on my knees. I decided to quit. I occasionally showed off my moves at weddings and other parties. Yet, by the time I obtained my doctorate and a friend suggested that I participate in Dance Your Ph.D., my skills were so rusty that I passed on the idea.

I really enjoyed dancing salsa, though. Eventually, I spent five hours at the dance school each week, learning both salsa and other Latin dance styles. After moving to Germany, I found new salsa teachers. I missed the great atmosphere of the dance school in Groningen, though. When the pandemic started, I dropped out, and I haven’t taken dance classes since.

Of all my past hobbies, I’m most inclined to pick up dancing again. I wouldn’t feel obliged to if it didn’t fit my schedule, though. Enjoyment and self-expression should be the central goals.

Singing

Despite playing the piano for many years, I didn’t really engage in singing until after completing my bachelor’s degree. That summer, a few of my friends invited me on a trip to Taizé, France. This small, peaceful town in southern Burgundy hosts a large religious community. While there, my friends encouraged me to join the singing practice. Admittedly, I couldn’t sing very well initially, but I threw myself into it enthusiastically.

A year later, following my second visit to Taizé, I joined a symphony choir and gained my first experience with giving concerts. When returning to Groningen for my PhD, I again joined this choir. After a while, I managed to get into the chamber choir of the same association. I also became involved with a small choir that organized local services in the style of Taizé. Supported by singing lessons, I eventually sang solos there.

I hoped I’d one day be able to sight-sing, that is, sing choral music directly from paper while seeing it for the first time. I wasn’t nearly as skilled as some of my fellow singers, however, and I had to work hard to keep up with the chamber choir. I felt insecure about making mistakes as well. By the time our harsh conductor made stress prevail over joy, I dropped out of that choir but maintained the other two.

After moving to Germany, I considered picking up singing again. Loving their repertoire, I was specifically interested in chamber choirs. I ended up joining a more casual choir, though. Although I didn’t always enjoy the music we sang, that decision had a clear advantage: I didn’t have to practice so much. I stayed in this choir for several years, enjoying the social atmosphere and highlights like the first concert after the pandemic.

After moving again, I participated in several one-off choral projects, but I haven’t committed to a choir since. Meanwhile, I’m not nearly at the level I was once at. I can’t read or sing music as well anymore, and my voice seems to have become hoarse. I might enjoy singing again, but I’d have to let go of the high expectations I had previously. I’d also have to overcome the fear of making mistakes. Otherwise, I’d be fighting a constant battle instead of engaging in a potentially enjoyable hobby.

Languages

In secondary school, I followed courses in Dutch, English, French, German, Latin, and Greek. Despite the sheer number of language classes, I was more interested in the natural sciences. I only took the compulsory introductory-level French and German. I dropped Greek in favor of philosophy and mostly followed Latin to obtain a Dutch gymnasium degree, which adds a classical curriculum to the general pre-university education.

Years later, after pursuing degrees in physics and mathematics, my stance on languages had changed: I thought it’d be fascinating to become a polyglot. Next to my native tongue, Dutch, and the other language I spoke fluently, English, I wanted to learn Spanish and Italian. I also wanted to expand my rudimentary knowledge of French and German to become fluent in all these languages. I spent some time studying Spanish before going on a hike to Santiago de Compostela, and I learned some words along the way as well. Trekking through France for about two months, I also got to brush up on my French.

By now, my French has become so rusty that I have trouble ordering food at a restaurant. Understanding ads and signs is as far as I get in Italy and Spain. Having lived in Germany for over seven years, I do speak German fluently. My goal to become a polyglot proved to be too ambitious, though. Even while immersed in German, I needed years to—remotely—approach the native-speaker level. And I haven’t been able to master any languages on the side. But I don’t need to either, do I? I’ll stick to the languages I regularly use and enjoy the few foreign words I pick up when traveling.

Contacts

During my studies in physics and my subsequent PhD at the same university, I met thousands of people. In some semesters, I’d interact with hundreds of people each week. Obviously, I didn’t engage with each person, but I was staying in touch with dozens of people simultaneously. Even when more and more of my fellow students finished their studies and took up jobs elsewhere, I met new people through singing and dancing.

Several developments drastically reduced my social circle. First, my partner and I moved to a different country. We still visited friends and family back home, but at most ten people visited us more than once over the five years we lived in central Germany. Secondly, the pandemic hit, which at least partly explains the previous point. I also took up a new job, which made me less flexible in planning trips and visits. Finally, my partner and I became more focused on ourselves and our lives.

On the one hand, I thoroughly enjoyed the busy years in which I interacted with many people. On the other, I appreciated the quiet of the pandemic. However, my mind didn’t adapt to the changes in my life very quickly. Although the pandemic and distance made it difficult to meet friends, I tried to stay in touch with them. Without face-to-face contact, that was hard. Over time, answering calls, emails, and messages became an ever stronger obligation.

On a Friday afternoon at the beginning of this year, I suddenly had enough. I looked at an inbox full of emails I once wanted to follow up on and started archiving them. I occasionally replied to an email or carried out a practical task. But I mostly set myself free from having to reply to conversations that, in many cases, had been dormant for more than a year and, in other cases, were up to five years old. The next day, I cleaned up my other email accounts and combed through my instant messaging and social apps. After two days of work, only a handful of messages that I wanted to answer remained.

I felt so relieved. I hadn’t only cleaned up my emails and messages, but I had finally broken through the obligation to answer every message I received as well. That’s not to say I intend to break off contact with the people I haven’t answered. However, when I get in touch with them, I want to do so from a place of enthusiasm, interest, and joy, not of being behind.

Blog

Last year, I needed approximately six months to go from the idea of setting up a blog to sharing my first story. During that time, I alternated writing with creating my personal blog platform. Once it went live, I thought I’d manage to post a new piece every week. Initially, I did, but I quickly realized I wouldn’t be able to keep up this pace. I then adjusted my goal to release two posts per month. Spending most of my free time writing, I reached this goal during the remainder of 2025.

Although I’ve really enjoyed seeing the results of my efforts, I can’t realistically maintain this tempo this year. I simply don’t have enough time for it. Besides, I’m planning to write a few longer stories. Therefore, I’m now aiming to post to my blog once a month. As you can hear, I’ve lowered the bar, but I’m still setting a target. When will I allow myself the freedom to share a story whenever I finish one—even if it takes longer than desired? With its wide scope, the present piece may very well bring me to that point faster than expected.

Science

Studies

During my studies, I followed dozens of courses in physics and mathematics. I aimed for high grades and diligently worked on my assignments. As a result, I built up a good foundation in my fields of study. Many of the more advanced courses expanded upon and helped me practice the earlier ones. Similarly, by supporting younger students as a teaching assistant, I stayed fresh on the basics. That wasn’t enough for me, though. I believed I needed to retain everything I had learned.

In contrast to most of my fellow students, I didn’t immediately sell my textbooks after passing exams. Instead, I kept the books and intended to study them again. In practice, it was hard to follow up on this intention. New courses demanded time, and I wanted to spend time with friends as well. Consequently, I kept holding on to my textbooks after graduating, convinced I’d revisit them someday. Again, that expectation was unrealistic. During my PhD, I returned to a few books, but I didn’t touch the others.

By now, I have—reluctantly—sold or given away most of my textbooks. To let go of the remaining ones, I need to look back critically. Were my studies really aimed at making me remember every possible skill, technique, and method? Did they strive to take me to some ultimate level of knowledge? No. I couldn’t have learned everything there is to know about physics and mathematics in five years. As I experienced during my PhD, I’d have to take a deeper dive for any specialization.

The goal of my studies was to develop a broad set of problem-solving skills. I could later select and expand upon any method I’d need. In other words, I never needed to stay fresh on every skill I’d learned. I can brush up on whatever knowledge I require whenever the time comes. I might as well do away with the remaining textbooks from my studies, then.

PhD

Aiming to improve predictions of the behavior of turbulent fluid flows, I spent the larger part of my PhD developing and evaluating so-called turbulence models. Turbulence models are designed to capture flow features that are too costly to compute in simulations while maintaining accurate flow predictions. At the beginning of my PhD, I became very interested in a specific class of turbulence models: nonlinear models based on the velocity gradient of fluid flows. I analyzed these models in detail and wondered how I could create new ones.

Subsequently, I developed a framework of constraints for modeling turbulent flows. I presented the first version of this framework in a well-cited journal publication. While writing my PhD thesis, I refined and added several modeling constraints. Originally, I intended to publish these new results in a journal as well, but I haven’t done so thus far. Since I obtained my PhD degree over five years ago, I will most likely not get around to it anymore.

In a project springing from a summer program at Stanford University, I applied the modeling framework to study rotating turbulent flows. After collecting the project’s results, I prepared a preprint and submitted it to one of the most prestigious journals in the field. Devastated about the manuscript’s rejection, I turned to assembling my dissertation. I’ve never improved or submitted the preprint to another journal. By now, my co-authors probably don’t expect me to anymore.

While writing my dissertation, I was again gripped by nonlinear turbulence models, and continued to examine how the velocity gradient could characterize fluid behavior. I included the results of this project in my thesis, but didn’t submit them elsewhere. For several years, I aimed to follow up on this work and forge it into a scientific publication. Next to my work and other activities, I haven’t made much headway on that task, though.

Software and programming played an essential role throughout my PhD. I applied and extended simulation software to study the behavior of turbulent fluid flows. I developed a computational toolbox to analyze the properties of turbulence models. I also wrote numerous scripts to process and visualize simulation data. I hoped I’d one day find the time to modernize and optimize the software I was using. I also wanted to open-source the resulting code. However, the emphasis of my PhD projects was on producing research findings rather than software. In the end, I’ve only published the turbulence modeling toolbox.

I’d love to continue doing research. In fact, since receiving my doctorate, I have made several attempts to revive my scientific projects. For example, I’ve started creating a few new research software packages. However, I haven’t been able to combine that work with my career in industry and other activities. I graduated over five years ago. I’m in a different field of work now. Everyone who was involved at the time will long have given up the desire to see the open ends of my research finished. It’s time for me to let go of all the work I think is unfinished as well.

Programming

Hobby projects

While writing my PhD thesis, I became interested in board games. Initially, I frequently played Boggle, a word game in which you need to find words in a grid of letters. While playing, I often wondered how many words were hiding in a given grid or how I could find the longest word. I began developing a command-line program to answer these questions. Later, I set out to create a web-based Boggle solver as well. I’d still say that developing such a solver makes for a nice hobby project with ample opportunity for extension. But I’m not going to devote my time to it anymore.

After my PhD, I created a web scraper that used Google Scholar, ResearchGate, and other sources to determine how often my scientific publications had been cited. I planned to extend this application so it would automatically extract metadata of any referring articles. I also intended to make my citation scraper publicly available. However, I haven’t worked on this project for almost four years, and I won’t touch it again.

Educational projects

Instead of studying computer science, I opted for physics. Hence, I encountered many new concepts in my first job as a software engineer. I worked with a host of new applications and tools. I came across data types and structures. I read books on design principles and patterns. I learned about various computer algorithms.

To practice and expand my newly acquired skills, I set up several tutorials explaining programming-related tools. I also created custom implementations of commonly used algorithms, design patterns, and data types and structures. I showcased some of my work in an online project portfolio.

In my portfolio, I initially applied the programming language I was also using at work. I intended to expand my tutorials and practice projects to multiple languages, however. That goal proved to be too ambitious. I didn’t manage to cover different programming languages. In fact, I didn’t post more than a handful of tutorials and explanations of computer science concepts.

I haven’t looked at my practice projects in a long time, and I no longer aim to. So, I might as well leave these projects be and archive them.

Courses

In my first software engineering job, I bumped into a new online platform for learning programming. The high quality of its theory sections surprised me, and I liked the quizzes and programming assignments. Most importantly, the platform offered a plethora of practical, step-by-step projects. When I left my job, I didn’t feel skilled enough to enter another one right away. Instead, I threw myself into this learning platform.

I first took a fundamental course in computer algorithms and data structures. Next, I spent three months finishing several very extensive programming courses. All the time, I felt like I had to complete more courses. I wanted to sharpen the skills I had acquired thus far and expand my knowledge of other programming languages and fields, most notably in back-end web development.

I love learning and developing my programming skills. I would love to follow more programming courses. However, I’ve been working as a full-stack web developer for some time now and learned a lot on the job. So, I won’t finish those lengthy courses on back-end development anymore. In fact, I’d like to avoid spending any unpaid time pursuing programming certificates. My professional experience has sufficed to find new jobs so far, and I’d surmise this will be increasingly so in the future.

More projects

With a Dutch world champion, darts was a very popular sport when I was young. It wasn’t until decades later that I began following the end-of-the-year championships, though. Obviously, darts isn’t a very physical sport. Still, I find watching people attempting to hit fields as narrow as eight millimeters from almost two meters distance surprisingly entertaining. I’ve also been impressed by the speedy mental arithmetic required to calculate scores and remaining points.

Shortly after I started watching darts, I found myself wondering how many ways there are to finish a game’s leg. Then, in the wake of my PhD, I set out to develop a program to determine how many of these so-called checkouts there are. At the time, I didn’t finish the project, but I came back to the idea a few years later. I then built a command-line-based checkout calculator, practicing design patterns and other aspects from the courses I had followed. I also set up an extended set of tests to verify the validity of the program’s output.

When my darts calculator was finished, I released it as an open-source project with detailed documentation. I also generated and published a dozen pages with comprehensive checkout tables for different types of darts games. Initially, I occasionally supplied my program with software updates. I also planned to create a web version of it. I don’t anymore, and I won’t maintain the command-line application any longer either.

P.S.

As I was writing this blog, I experienced that letting go of ambitions is hard work. Still, I’ll abandon one more endeavor. However aspirational my intention for this blog may have been, I will not finish the list of goals I’m leaving behind.