I taught a body alignment and breathing class yesterday at a v. big world-wide corporation.  I normally teach a physically challenging class...  This one was mentally challenging.  The students were instructed to pay more attention to their exhales rather than their inhales.  Relax their teeth, jaws and lips and only breathe through their noses.  If they had a thought, they were instructed to breathe louder and take in and push out more oxygen.  Add lots of complicated movements and it is a standard class.