The thing with rock climbing is that it is not just "excercise". It's a hobby, it's fun for those of us that do it. (And if it isn't fun, why are you doing it?). I don't climb to stay fit, I climb because I enjoy it, because it is a challenge. I have a fear of heights, so I get a huge adrenaline rush when climbing. There is nothing like abusing your fears to produce thrill ;)