The Algorithm of Age

In the bustling world of tech startups, where burning the midnight oil is often a badge of honor, Felix Geilert is an anomaly. As the co-founder and CTO of the AI healthcare company Radiant Science.io, he is no stranger to intense pressure and demanding schedules. Yet, his personal operating system is built not on caffeine and adrenaline, but on a deeply systematic, data-driven approach to health and longevity. His goal is not just to succeed in business, but to achieve a feat no human has before: living 140 healthy, vibrant years.

We sat down with Felix to understand the mindset behind this ambitious mission. How does an engineer think about his own biology? How do you separate scientific signal from wellness noise? And what can we all learn from a life lived with radical intention? This is a blueprint for anyone looking to move beyond passive health and start actively building their own longevity journey.

The Spark

What was the specific moment that turned your general interest in health into a dedicated longevity mission?

There wasn't a single moment, but rather a series of key turning points. It began during my student days around 2012. I was living very unhealthily frozen pizza, pasta, the usual cheap student fare. A few vegetarian and vegan friends in my dorm inspired me to start cooking with them and explore healthier eating. This unlocked a curiosity about nutrition and how food influenced my energy.

The second unlock came from reading books by Canadian triathlete Brendan Brazier, who focused on building a nutritionally dense diet. I started experimenting with his recipes and, despite the cost for a student, I noticed a real difference in my energy levels. It highlighted that not all calories are equal and drove home the importance of food quality.

Your bio at Radiant Science mentions a goal of living to 140. What is the personal significance behind that specific number?

The final turning point was in 2020. My first big job at Microsoft gave me the financial means to experiment more seriously. I read Lifespan by David Sinclair, which is where the 140-year goal originated. I discovered figures like Bryan Johnson and realized that extending lifespan wasn't just empty words, it was rooted in scientific insights.

I chose 140 specifically because it's ambitious but not fantastical. The oldest person lived to around 122, so it's a stretch goal that forces me to rethink conventional approaches. To reach something that nobody has reached before, you need to do something different. This number is a constant reminder of that. Of course, the goal is 140 healthy years. It’s about healthspan, not just lifespan. This mission became a reinforcing loop: the more I optimized through testing and protocols, the better I felt, which in turn deepened my motivation.

The Engineer

As a CTO focused on AI, how do you apply that engineer's mindset to your own health data to optimize your biology?

The core idea is to break it down. It’s an alignment problem: how do I align my specific routines with my health goals? I think a lot about synergy, combining frameworks, and using data to show me what is working and what isn't to get the maximum effect.

This requires three things. First, flexibility to experiment. Second, a deep awareness of how your body feels, which is something I developed through meditation. And third, you need to collect data. This can be quantitative from my Apple Watch, or qualitative, like journaling in an Excel sheet about how my body feels. This data helps me realign my life structure, especially during periods of transition.

The longevity field is full of hype. What's your personal framework for testing a new protocol or deciding what's credible?

This also comes back to an engineering mindset. When I see a new, hyped protocol, the first question I ask is: what is the risk? Could I die? Could I get cancer? What are the unknown side effects, the "unknown unknowns"? Some things, like most supplements, are very well-known and low-risk. Others, like molecularly changed supplements, might have more severe side effects.

Next, I look at the promised benefits and see if they align with my goals or address a problem I’m currently seeing in my data. If my omega levels are low, an omega supplement is a direct solution. Once I classify the protocol, whether it’s to fix a problem, for prevention, or for a general benefit, I devise a testing protocol. This usually starts with recommended doses from research papers. It’s your health, so you need to dig through the research yourself. Is an animal study really helpful? Do I want to take the risk? Was it a small cohort? AI tools can help, but they can also hallucinate, so you want to be 100% sure, so you need to read a lot. Just recently I tested collagen supplements and it gave me skin rashes, so obviously this protocol was ended.

What are the foundational “non-negotiables" of your daily health routine that deliver the most significant results?

Sleep is definitely one. I try to get at least seven, ideally eight hours, though that can be tricky in startup life. The one I make the fewest compromises on is food. I eat nutritionally dense food and adhere to my supplementation schedule. I meal prep for five days at a time, which takes about 30-40 minutes and makes it incredibly easy to follow.

The key insight is to make the things that deliver tremendous results, sleep, food, and exercise, as easy as possible, with very little friction. My meal prep is in the freezer, making it the easiest option when I'm hungry.

How do you structure your weekly exercise regimen to hit key longevity metrics like VO₂ max and strength?

I make exercise easy by having a home gym with weights and machines. I don't need to pack a bag or travel, I just go downstairs. This is obviously a privileged position, but building these systems over time is key.

Increasing my VO₂ max is currently a big item on my to-do list. I'm at about 58 and want to get above 60. For strength, I train three times a week with a protocol that splits up muscle groups: one day for legs and back, one for shoulders and abs, and one for arms. That works relatively well for me, but right now I am experiencing with HYROX training.

The Mindset of High Performance

How has your longevity practice impacted your performance in a demanding role as a CTO and co-founder?

It provides higher focus and, because the routines are so integrated into my life, it allows me to endure more stress. Startup life works in cycles of quiet periods and intense stress, like during a funding round or a product launch. Leaning on my routines during those times allows me to perform at a high level for way longer.

Recently, we had a crunch period of eight weeks. I don't think I would have been able to go through it without my longevity routine, at least not at the same level. It gives structure to the day, and because it’s already an established habit, it’s easy to follow.

Beyond the physical benefits, how has this journey improved your daily quality of life and sense of purpose?

The main benefits are concentration and resilience, which have a day-to-day impact. It also builds discipline, sticking to a routine creates an anchor in life when times get stressful.

As for purpose, the 140-year goal is a mission in itself. But it has also given me more energy to reach for higher goals in the startup as well.

The Future of Health

From your perspective in the AI industry, what is the most exciting health application we'll see in the next 5-10 years?

Five to ten years is a very long time, as technology moves on an exponential curve. But in the immediate future, we will see more personalization and democratization of healthcare. One of the largest unlocks will be the contextual adaptation of health protocols for the majority.

Right now, it takes a lot of effort to build a personal health protocol. In the future, AI can do more of that. For example, generic advice like "get sunlight every morning" is impossible for someone doing night shifts. AI that understands the context of your life can give tailored recommendations that are easy to integrate. This will be a key factor in broadening the audience for longevity.

As both a user and creator of AI in healthcare, what is your view on the balance between data privacy and scientific progress?

Living in the European Union, the right to your own data is really important. But we can't fall behind. The way to handle this trade-off is through proper communication. If we completely seal off our data, others will build the AI healthcare systems, and those systems might have different biases. When we apply these to our population, that could lead to higher failure rates.

There should be anonymization processes to collect general health data, with strict tracking to prevent unintended uses. But it's also about transcending boundaries so that people are part of the conversation when their data is used, much like in citizen science projects. We need to communicate clearly what is happening with the data and why it's needed to get people on board.

Wisdom for the others

For someone feeling overwhelmed, what is the most impactful first step to take on a longevity journey?

This loops back to how I started. The most impactful step is to take small steps and start with the fundamentals: nutrition, exercise, and sleep. If you can't get these basics right, you don't need the most advanced treatments, which only provide the last 20% of results. And by doing that find synergies, by for example doing morning yoga with your partner.

Another is that building habits starts small. If you want to exercise, start with one push-up a day. That doesn't sound like much, but it builds a routine. Once you've done one, it's much easier to keep going and do ten than to start with a goal of 100, fail, get frustrated, and stop.

When you picture yourself at age 100, what key physical and cognitive abilities define success for you?

Ideally, it’s not much different from where I am right now. I want to push out the decline of my body as far as possible. Success at age 100 means I can do the same things I do today: work out multiple times a week, maintain deep focus, learn new things constantly, and complete all my daily chores like cooking and gardening without any help. It's basically being in the same physical and cognitive condition as I am right now.

What is the biggest unanswered question in longevity that you are most excited to see solved?

Ultimately, longevity isn't one single metric. To truly solve it, we need to understand the more nuanced picture. The most exciting frontier is finding ways to not just slow aging, but reverse it. Can we self-heal our body to repair joint damage or scars and build it back to its more natural state?

On a smaller scale, I’m interested in things like Ozempic, not for myself, but because drugs like it lower the entry barrier for a large part of the population to live healthier. By eliminating a certain set of common diseases, we can focus our collective attention on other parts of aging, thereby extending both lifespan and healthspan for society as a whole.

Conclusion

Felix journey is a powerful testament to the idea that our health is not something that merely happens to us, but something we can actively build. By combining an engineers systematic approach with a deep sense of personal purpose, he is not just chasing a number, but designing a life of sustained performance, resilience, and vitality. His story serves as a compelling reminder that the quest to live longer and better begins not with a mythical fountain of youth, but with small, intentional, and data-informed steps we can all start taking today.