About
Built by a lifter, for lifters.
I'm Jelle Heijne, a 28-year-old mechanical engineer from Eindhoven, Netherlands. By day I work on hydrogen combustion engines. MuscleMind is what I build at night.
Why I built this
I've been going to the gym on and off since I was 16. And that's exactly the problem — on and off. Some months I'd train consistently and feel great. Other months I'd lose motivation, skip sessions, and lose the progress I'd built. When I did show up, I lacked structure. I'd record my lifts in Excel for two weeks, then stop. I plateaued.
I knew what I needed was a personal trainer who could keep me both structured and accountable — but I couldn't afford one. When ChatGPT came out, I saw the opportunity. If AI could understand my training history and adapt to my performance, it could do what a trainer does — without the €80 per session price tag. I spent two years building that idea into MuscleMind.
What makes it different
The consistency problem has two sides: structure and motivation. MuscleMind is built to solve both.
On the structure side, the AI Coach remembers every rep you've ever logged, every piece of feedback you've given it, and every week it builds you a completely new plan that progresses automatically from where you left off. Progressive overload — the principle that you have to consistently lift more over time to keep getting stronger — is built into every plan, automatically. You never have to think about whether you're actually making progress. You just follow the plan.
On the motivation side, every workout you complete earns you $MUSCLE — our in-app reward currency you can redeem for discounts. Showing up should feel rewarding. Trainers charge you. We pay you.
Built by someone who uses it
I'm not a certified personal trainer. I have no formal fitness credentials. What I do have is personal experience with exactly the problem MuscleMind solves — years of inconsistent training, lost progress, and frustration — plus a degree in mechanical engineering and two years of learning UI/UX design and Flutter development to build the solution.
I've been using MuscleMind myself for two months now. The difference is real. I train at the gym twice a week and I never walk in wondering what to do — I follow the plan, log my sets, and the app takes care of everything else. I'm making measurable progress, consistently, for the first time.
Credentials
Eindhoven University of Technology (TU/e). Trained to think in systems, feedback loops, and data-driven optimisation — which is exactly how MuscleMind approaches your training.
Designed, built, and personally tested every version of MuscleMind. Every feature is a response to something I experienced as a real user.
12+ weeks of logged sessions, progressive overload data, and measurable strength gains — all inside MuscleMind.
I built MuscleMind because certified trainers cost €80/session and most people cannot afford consistent access to one. The app is the affordable, always-available alternative.
Read the training science behind MuscleMind →
Get in touch
Questions, feedback, or just want to talk training? Reach me at musclemindai@gmail.com or use the contact form.