How about health?
How about looking good?
How about knowing that you're doing something worthwhile instead of wasting your life away by sitting in front of the TV?
How about setting a good example for those younger than you (or your friends, if you're young)?
How about aging less quickly?
How about not throwing your back out when you change the sheets on your bed?
How about the fights that you don't get into because other guys look at you and think, "uh, maybe not"?
How about increased attention from the opposite sex?
How about that oh-so-nice feeling of control that you have when you want to do something a little out of the ordinary with your body?
How about the sense of superiority you feel (and try to supress, but fail) when looking at the "typical" 30-, 40- or 50-something American?
How about all the knowledge that you acquire along the way?
How about the sense of camraderie you get with the other serious lifters in your gym?
That's about it, off the top of my head...