This app looks a bit like what I need, but not quite.

I practice martial arts, and would like to improve my overall fitness. Strength is obviously part of that training, but so are flexibility, speed, and reaction times.

I have yet to find a training plan that accounts for all these factors. Even worse, some of them tend to negatively correlate with each other: when done wrong, for instance, strength can negatively impact flexibility.

I thought this would be an easy problem to solve. But so far I've had no luck. I guess there is more to biology than just solving an optimization problem.