A simple breathing technique- Inspired from wim hoff( iceman).
It starts with Controlled hyperventilation, taking 30 deep breaths 3 rounds- Ending each round with last breath exhalation completely and than holding the breath  as along as one can, mapping breath retention time with a stop watch. The science behind this is with breath on hold  the blood vessels expands and  when one starts to breathe again, it  opens up all the blockages and re-programmes the whole cell anatomy.
The breathing and holding technique is than used in yoga postures, Meditation & Cold showers.
With practise one can influence the Autonomic Nervous System & consciously control immune system.  Achieve natural highs and greater focus.