Ok, I'm 16, I've been training in BJJ for the last 2 months or so and I love it. I just recently went to a sparring class and had to spar with a guy literally two times my size. I thought I was in pretty good shape until I sparred with him for about 5mins and I was so gassed after that, I was trying to take him down but that didn't work too well seeing that he's a green belt and I'm still white(of course) and he's 240 pounds and me, a lame 125 pounds. It was pathetic. I need a cardio routine to get me in shape since I'm entering a tournament in January. Thanks.