This sounds simple, but everyone seems to hold their breath. You get tired when you hold your breath. It happens in weightlifting also. Grappling is a crazy amount of cardio and if you hold your breath, you won’t last to the end of the match without quitting. Yoga has helped me with this a lot because you practice breathing in poses. Breathing helps calm you when you are panicking. The goal should be long, smooth breaths. Practice breathing after training and breathe only through your nose, counting in and out. Example: Inhale, 1,2,3, exhale, 1,2,3,4, pause at bottom. Breaths should not be choppy. Do this exercise for five minutes. While inhaling expand through your ribs. Imagine the air inside you. You can do this for the match.