The Zen of Ice Cold Showers
Piotr Prosol

Nice piece. If you’re not familiar with this already, you might want to explore the subject of freediving (extreme breath-hold diving), which takes advantage of “mammalian dive reflex” — an example of the sort of over-engineering of the human organism you describe here. If you can overcome the protective panic instinct, you can get to a place in which the cold and pressure of depth actually help your body use the air you inhaled at the surface more efficiently. Again, this is an activity one should only engage in with appropriate training and after getting approval from one’s physician.