Look for some very fit celebrities who made millions through their looks.
Do what they do.
Do what they do.
Health and fitness, physically, are indicators that (A) somebody has time to invest in their wellbeing, (B) actively invests that time (C) is more likely to survive illness, injury, etc. (D) is more likely to be successful due to social implications halo effect, yadda yadda.
I'm not going to argue that there aren't maladaptive traits related to health and beauty that pop up all over the place: physical ones like eating disorders, behavioral ones like narcissism.
But, "train regularly -- three to five times a week -- plus eat a high-protein low-processed sugar diet, like celebrities do when they're training for roles" is nowhere close to unhealthy excess. A lot of people just find it very difficult to do.
Reality: Fitness primarily means "these genes survived the winnowing process."
It's a little more complicated in that, for example, you see more mutations of genes (at least in germs) in high stress environments. But genes don't sit around asking each other how we are going to take over the world like little DNA movie criminal masterminds. Instead, the ones that don't die the most "win."