Guess I'll chime in, for the first time ever, in fact. I've been attempting to do something about my rather shoddy physique for years, but never found the will to really do something about it. Until now. Discovered a small gym nearby, and a friend of mine was already frequenting it. I talked to the people running it, and they gave me some great tips on what to start with, and how to progress. So now I go there three times a week (or at least that's my goal), doing mostly regular anaerobic exercises to build muscles, and finishing with intervals on the treadmill.
It ain't easy, but I figure that it's better to get going now while I'm relatively young, than wait and regret I didn't try and get in shape sooner.