I still haven't tried any of the breathing techniques, but the book published on Wim Hof's method[1] is a fascinating read. It was written by an investigative

I still haven't tried any of the breathing techniques, but the book published on Wim Hof's method[1] is a fascinating read. It was written by an investigative journalist that was initially skeptic of the method, and decided to debunk the myth. [1] What Doesn't Kill Us: How Freezing Water, Extreme Altitude, and Environmental Conditioning Will Renew Our Lost Evolutionary Strength https://www.amazon.com/What-Doesnt-Kill-Environmental-Conditioning/dp/1623366909 https://www.amazon.com/What-Doesnt-Kill-Environmental-Condit...