Obviously I do not know you personally and can't speak to your conditioning, but it may be a combination of both. No one would argue that smoking doesn't harm your cardio and lung capacity and I am sure any coach would pressure their fighter to quit smoking (as well as any doctor, beyond fighting reasons). With that said I think it is safe to say the Lentz is more of an exception than he is the rule.
Still, I am sure intense cardio training can combat some of the detrimental cardio-effects of smoking.
Team Stand Alone #1