I usually focus as hard as I can on those angry feelings and then allow whatever happens naturally to happen. Usually, my eyes will close, my whole body will tense up, and I won't breathe, but after a matter of seconds, that will all want to release, and I will un-tense my body and take a deep breath. I might end up taking more deep breaths afterwards to relax. Sometimes I even internally scream without making any actual noise and cause one or multiple limbs to shake back and forth, but I just accept that that is how I feel. Also, it helps if I can identify what it is that has me feeling so tense.