I've always been a natural distance runner, swimmer, cyclist etc. I can do anything that envolves long term endurance fairly well without training. For example, a few years ago when I was training martial arts pretty hard, I decided to enter a 5km race (a fairly big one too) and having never run even close to that far before, I placed 4th overall and first in my age class. I've since been out of training for a while and am just getting back into it. Lately I've been finding that my lungs have been suffering quite a bit while doing cardio. During my hiatus from martial arts, I smoked a lot of pot which didnt help (I've quit that completely). My legs never seem to get tired while I'm training either. What I'm looking for are some routines that will help me get into better shape for sparring, bag work, pad work and rolling. My schedule is pretty busy and I'll only be able to fit in cardio specific training once or twice per week; however, I do get a lot of cardio in class as well.