This is a bit like a 'constant' heimlich manoeuvre - get into the habit of breathing from your diaphragm, not merely expanding your chest area. It may help especially in the anxiety situations as you find you can take longer, deeper, steadier breaths - that's how singers are able to hold notes longer and control their volume - you get what I'm going to say next - better peak flow and lung capacity.
I do have asthma caused by the chemicals I used to work with (but fortunately I'm away from them now), It never affected my breathing too much because I'd also been trained how to sing so strangely, I don't need any meds prescribed! The only time I have major problems is when I get a cold or chest infection.