How to improve my cardio? Recently moved up to intermediate classes at my gym. 5'10" 195 fast explosive and can hit and kick hard , but my gas tank is absolute shit. But I guess that's the tradeoff with that build. I'm no Nick Diaz. Got lots of TypeIIX fibres (like grandma who was a 100m dash athlete) making me extremely quick and powerful for about five minutes, then the lactic acid builds up and my power drops by like 60-75% and I'm moving around in slow motion like a zombie or punch drunk Rocky trying to keep hands up. I'm a med student at college most of the time and sit at a desk 8 hours a day studying. Resting heart rate used to be 100 before I started training; it's 79 now. I try to go for a 20 minute walk every day. I train MMA kickboxing and BJJ 1hr/week each; so 3 hours training every week. Tried to go for long runs (25 min) to get better but this didn't change things much.…