LOL, you guys.
Actually, you are <i>re</i>learning how to breathe from your diaphragm. Babies instinctually breathe that way (see <a target=_blank class=ftalternatingbarlinklarge href="http://www.ehc.edu/studentlife/breathing.pdf">http://www.ehc.edu/studentlife/breathing.pdf</a> ).
When you breathe from your diaphragm, you are using the lower lobes of your lungs more. Some with bronchiectasis (CF) have crappy lower lobes. This is in part because they have trouble getting the air deep into them so they can cough stuff out and clear them. -- and then once those lower lobes are crappy one's body sort of doesn't think of even trying to use them and just pulls air into the upper lobes (shoulders, not diaphragm).
Not to mention that one's instinct when one is short of breath is to try to get more air in rather than worrying about getting air out -- and during the panic that one feels when one can't get more in it entirely escapes one that the reason for that is because there is already air in there (just CO2-ridden air). Or the fact that the less you use your diaphragm the weaker it gets.
It's a vicious cycle thing.
But with some conscious thought for a while you can stop the cycle. Breathe correctly, get a stronger diaphragm, work on those lower lobes again, etc.
Good luck to you.