Don’t get the wrong idea, this isn't a suggestion to engage in some Opus Dei corporal mortification. The technique of practicing voluntary discomfort dates back, again, to the ancient stoics and was used to strengthen the mind and body. It was a way to force someone out of complacency and help build the fortitude to handle life’s challenges. They sometimes took cold showers, slept on hard floors, and fasted. The Getting Stronger blog sums it up nicely, “The Stoics did not shun worldly goods and pleasures or embrace discomfort out of masochism or to pursue spiritual atonement or purification...Rather, the Stoics advocated occasional, deliberate use of temporary poverty, voluntary discomfort, and refraining from pleasures in order to quiet their appetites for material goods and sensual pleasures, increase the sense of appreciation for what they already had, and — most importantly — to “immunize” themselves against future misfortune and develop the courage to take on difficult challenges.”
So, go ahead and take a cold shower…get bulletproof.