There is no physical output to acquire but it's not for nothing. In exchange you get a natural anti-depressant and a good load of positive hormones. On top of that you get fitness that can be used at any time for any situation and you get muscle mass (that has positive side effects) and hunger suppression.

All in all, it's not bad for something you almost get for "free".

But you can also choose to enjoy life, get fat (in moderation) and die a bit earlier. As far as I'm concerned that also a valid choice, depends on what you want from life...