I wish I could give you a solution, I too do this it can last a whole day! But the only thing that helps me is doing something else like going for a walk etc , some days it helps and some days as soon as I'm back home I focus on breathing again, I find sometimes lying down watching tv helps
try to meditate for a few minutes[ quiet the body quiet the mind]
Try focused breathing techniques like musicians. Breathe in through your nose, out through your mouth. Slowly. Exhaling fully. You need to fill your diaphragm, your stomach extends.