So my friend has been training to fight me lol because he knows he'd lose I am in very good shape I'm not being cocky but im quite heavily muscled but he is taller and has better cardio but i can literally smoke him in wrestling if i wanted to I could break his limbs. What are some very good cardio vascular exercises, I am a weight lifter. I also have him way smoked in the speed department but I want to be able to fight for about 20 minutes without getting tired, like a UFC fighter, how can I do this?