I really believe that deep breathing takes the edge off any stressful situation. I know that sounds like such a cliche. I swear it works ,  the breaths have to be so deep your stomach actually starts to fill full.  I would hold it for about  10-15 seconds and let is out very slowly .. out of your nose is the best. The key to this excersise is to think about all the  toxins in your body leaving with that exhale.   For example, if you just had a fight with your teenager. ( it happens lol) then as you are exhaling think of all the dark and tight feelings this fight just conjured up ... as you are exhaling they are being stirred up inside and they are leaving with that deep exhale .  

The fight probably would cause anyone to feel angry, stressed and  anxious.  If you can imagine those feelings as if they were tangible , like sludge from your engine , or grease left over from your turkey dinner.  Then your deep breath is like a sponge or a vacuum  sucking up  that sludge out of your chest ,and as you exhale you are blowing it all out of you. 

Those feelings can pile up if you don't purge them .  Then your stress level is lessoned.   The actual physical aspect I will cover later.  IT takes a while  for the  stress homones that you summoned up to disappear . You can move that process along.   

You are in control of how the stress affects you.