How will body building affect my health later on in life?

For the better: Everyone i know who's tried Anabolic steroids has been sorry; if you try for super-heavy weights you can hurt your joints; if you become massive, you'll have loose skinfolds if you stop. Otherwise, the bodybuilders i've known have aged remarkably well, having learned good eating & fitness habits. You'll have more muscle fibers even if you stop (muscles have a memory). Encourage you.