you should learn how to breathe in and out for extended amounts of time. start with breathe in for 5 sec, breathe out for 5 sec. always try to take more air in than you can. then try it for 10 in 10 out.then try it again for 10 in, hold for 10, then 10 out. There are a lot of exercises you can do. Try looking up "the breathing gym" for more exercises.
There are two ways you can do this 1) you can learn how to control your heartbeat 2) you can do alot of cardio exercise which should expand the lungs also don't smoke or inhale gasses you shouldn't.