Exercise acts as a hormetic stress, potentially priming the body's stress responses to be more resilient.

“Yeah so that's one idea is that it's hormetic stress meaning it's low level stress that then primes everybody else, all your other stress responses to be hyper-vigilant. And so then when a bad telomere comes along, or an insult from radiation or high sugar because you just couldn't resist that last brownie, you're better able to deal with that stress.”