Clean natural organic (when available) non gmo foods is the key to longevity. People accept lethargy, aches, pains, disease, etc etc as a part of getting old. It's bs. Getting old doesn't mean your body falls apart and becomes racked with disease and pain. Years and years of poisoning the body with chemicals found in foods leads to a lot of these problems. Keep putting a dropper full of poison into a a pristine lake everyday for 50 + years and watch that lake turn into a cesspool of disease and decay.
Isn't that exactly what getting old is? The body stops working efficiently?
Don't get me wrong, poor diet can certainly hasten that along or cause its own problems, but it's not as though aging won't happen if you 'eat right', or that you'll be completely fit and as strong as you've always been until the day you die.