Could make seperate skills that when you level them up to certain points, it increases the associated stats, similar to stats through skills, but add activities ingame (like strength workouts with equipment) that contribute more.
I’d think that would be a good part of it and agree about the workout stuff, I think it could (and should) have a broader scope then just being tied to skills.
With the stuff about being overweight/underweight going in it seems like muscle mass and working out could tie nicely together with some of that stuff. More muscle needs more calories and decays if you stop exercising or something.
Atrophy, muscles atrophy if you don’t exercise them at all for a lengthy period of time.
God help us if they just decay, the amount of medkits we’d burn through.