Maggie's Farm

It has become a casual consensus that exercise, or at least daily vigorous movement, enhances one's immune response. 

Anecdotally, it looks likely. But the catch is that it's the most fit people who do an hour or so most days, so is it causality? Statistically, fitter people are best prepared to deal with the attacks of nature: better disease-resistance, better healing, etc.

People with physical jobs do not need to think about it, but most of us do. In a way, daily exercise is an attempt to recreate a bit of what humans were built to do.

I feel that exercise (The Maggie's Fitness for Life program, especially) has the main goal of maintaining functionality and vigor for as long as possible. Sure, looking good matters too, in life. Nutrition for weight, exercise for strength.

Re immunity:  Exercise could bolster immunity in a variety of ways.