As a singer, I’ve been trained since early high school in the proper breathing technique. One should always breathe from the diaphragm. Your shoulders should never move up; instead, your belly should move out as you take a deep breath.
So now, of course, I have to do exactly what I’ve been trained not to do: to take a deep breath, I have to shrug my shoulders and hunch my back to give my lungs the room to expand. My tummy is just too tight for deep breathing yet.