The repair of the wear and tear seems to provide more opportunities for the body to reject cancers. Also, aerobic activity may encourage selection for oxidative

The repair of the wear and tear seems to provide more opportunities for the body to reject cancers. Also, aerobic activity may encourage selection for oxidative metabolism which is very suppressed in most cancers. It's counterintuitive but the epidemiology is very clear that exercise is protective. It doesn't wear you out faster but rather helps you rebuild and maintain yourself more rapidly (without which, you wear out).