I've smoked since I was fifteen. Still do. Wish I'd never started. Though, to be sure, when I was growing up, most everybody smoked. And contrary to popular belief, this country wasn't founded on or for political or religious differences—it was founded and grew on tobacco.
I'd be a hell of a cyclist if I didn't smoke, but I do and it doesn't seem to to hurt me that much (at present). I keep up and can lead pace lines and can generally ride further/faster than an awful lot of my non-smoking friends. I rode a few days through the Appalachians this Summer with a fella my age (51) and we were equipped pretty much the same. He was a health freak; didn't smoke, drink or have any vices and would work out. It used to tick him off that I'd be waiting at the top of a climb for him having a smoke. Then again, his comfort zone was so narrow that I'm surprised he ever got on a bike to ride across country or even ride with me as long as he did.
What bugs me is some peoples "holier than thou" attitude towards smokers. If I'm not making you breath my smoke then please don't go out of your way to criticize me. Happens quite a bit. Somebody's gonna catch me at the wrong time on the wrong day one of these times. I guess it's one of things that lets them feel better about themselves, or perhaps superior to folks who smoke. Eff 'em, I say—mind your own business.