In his video „The relation-ship between breathing and anxiety“, Buteyko breathing practitioner Robert Litman speaks about his own breath experience and his path to breathwork.
He then introduces basic nose breathing excercises and explains how the fight-or-flight response is caused and/or maintained by mouth and upper chest breathing. He goes on to demonstrate an excercise for dealing with panic attacks and also addresses the subject of breathing for performance.
What I appreciate about Robert Litman is his gentle approach to the Buteyko method and how he always puts an exercise in the context of the experience of breathing.