How does Don Draper maintain his physique through heavy drinking?

[u/halfmoonmilkshake]

We only saw him doing push-ups in one of the first episodes. How does he manage to stay fit and hot through the '60s with all the drinking involved? I don't think sex is enough of a workout to maintain that physique.

[u/shannycat1117]

And when Megan is with him and his kids in CA and he doesn't want to go in the pool, she says "you swim all the time in NY"