Check out this video on YouTube:
Wim Hof has scientifically proven that he can control his immune system and negate the affects of temperature all by using a simple practice of breathing.
He had climbed Mt Everest on shorts and no shirt. Run a marathon in the desert without water. Broken a world record for swimming under the ice.
All this achievement from a simple breathing exercise. I’ve enclose a small sample of what he teaches but suggest you look into it for yourself.