You may be surprised at how early aging can kick in for some people - many start showing visible signs by the time they hit 30. I point this out not to frighten you, but simply as a reminder that aging isn't something that should be ignored till its effects are irreversible. Those who want to stave off the effects of aging for as long as possible (and possibly reverse some of them) will obviously need to engage in a regular workout routine, and healthy eating habits, but the other key part of the fitness equation is choosing the right dietary supplements.