Another bullet point on how exercise helps fight disease from Dr. Mercola:

Ever wonder why Jack LaLanne keeps on chugging along into his 90s, looking and sounding as vital and healthy as he ever did on his TV program 40 years ago? A review of studies reports exercise slows down the effects of aging and help a person maintain his or her cognitive abilities as they get older, more evidence that physical activity — not a drug — can do wonders for your mental and physical health.

For instance, seniors over age 65 who exercise for only 30 minutes three times a week have a better chance of avoiding Alzheimer’s disease, even if they’re predisposed to it than those who don’t.