One issue is that skills don't last forever. You lose them if you don't practice (and I'm not even talking about body decline). And you can't practice them all

One issue is that skills don't last forever. You lose them if you don't practice (and I'm not even talking about body decline). And you can't practice them all at once due to time limitation. Besides, some skills decline slower than others. For instance, "technical" sports, such as skiing, boxing or swimming, seem to be more engrained in the body. Whereas running abilities decline pretty fast. I usually favour technical sports for that reason.