Well, I am an ex-smoker of 16 years now. I've quit for a total of 2 years. My sensei is 60. In TOP shape and smokes. Does it hamper him? Not really, he doesn't smoke while he practicing. Well martial arts stamina should be like boxing stamina, in spurts. Your aerobic level shoud go one round peak and then come back down, go another round peak and then come back down. As opposed to a marathon runner that is constantly at a high aerobic level. Karate is about explosive power. An explosion and then retraction. Not a constant stream of power. The best and ONLY way I found to quit was the "out of sight, out of mind" philosphy. I've tried just about everything: Gum, Patches, etc etc. nothing worked. What I found was that I could break down my smoking cravings with certain events or emotions. For instance, - I wake up in the morning, I want a cigarette - After finishing a meal, I crave a cigarette - When I start my car, I want a cigarette - I'm at a club having a drink, I need a cigarette - When I play poker, I want a cigarette Well you get the gist of that. Any situation I found myself craving a cigarette I just wouldn't do anymore. So I stopped playing poker, stopped drinking, stopped going out to clubs... sounds pretty boring aye? Well obviously I couldn't stop eating food, driving my car, or waking up so those were the hardest to overcome. BUT At least you have cut down more than HALF of your cigarette consumption JUST by avoiding other places you've associated smoking with. Now i'm not saying to stop doing that stuff forever, but you need to give yourself mental strength to be able to go to a club and not want a cigarette.