Mr Scott Carney explains the mental and physical rewards of discomfort.

What doesn’t kill you makes you stronger, as Ms Kelly Clarkson famously articulated. And while clearly there are exceptions, the principle is shared by author Mr Scott Carney, who has removed at least one caveat by climbing Mount Kilimanjaro with no shirt on.

Indeed, his new book What Doesn’t Kill Us holds that the reverse is also true. Mollycoddling mod cons such as central heating, rather than protecting us from the elements that our ancestors withstood perfectly well, are in fact weakening us as a species. Only two kinds of animals get fat: humans and our pets. (Conversely, studies show that you can lose weight while you Netflix and chill simply by turning down the heating a few degrees.)

Mr Carney’s quest to discover civilisation’s lost gains takes him from the top of Africa’s highest peak to lifting weights at the bottom of a Los Angeles swimming pool alongside Mr Orlando Bloom. The real star, though, is Mr Wim Hof, a Dutch guru who holds 26 world records, including the longest ice bath, and claims to be able to manipulate his body temperature via a programme of breathing exercises and cold exposure. Desk-jockey journalist Mr Carney initially set out to debunk Mr Hof. Instead, he became a loyal disciple who followed “the Iceman” and his methods all the way to Kilimanjaro’s snow-capped tip. (Mr Hof summited in just shorts.)

If that sounds a little too extreme, then below are three ways to reap the physical and mental rewards of discomfort without mountaineering in a state of undress. Because MR PORTER can’t in good conscience recommend wearing fewer clothes.

Mr Hof makes new arrivals at his Polish training camp stand semi-naked in the snow for six minutes, building up to an hour after four days. But you can enjoy some pretty cool benefits with just a 30-second blast of icy water. That’s enough to fire up your stores of brown fat, what Mr Carney calls “the missing organic structure that separates humans from the natural world”. Found mainly in your back and shoulders, subcutaneous brown fat keeps you warm by burning the wobbly white kind around your midsection (as many as 400 extra calories when activated in one study subject). Boosting metabolism and circulation, cold showers also improve recovery from exercise, immunity, alertness and productivity (by bracing you to surmount obstacles). And despite their reputation for mood-dampening, they have an opposite, antidepressant effect. Perhaps most importantly, cold water doesn’t dry out your skin like hot water, and it closes your pores to prevent not-so-hot breakouts.

If you’re starting to hyperventilate ahead of a big deadline or presentation and you don’t have time to do an emergency Headspace meditation, try sticking your face in a sink of cold water. (Maybe wait until the office bathroom is clear first.) This immediately triggers the mammalian diving reflex, an automatic evolutionary response to submersion located deep in what is dubbed your llizard brain, the oldest part, which is responsible for your most primitive and powerful survival instincts. As Mr Carney explains, your respiration and heart rate slow while blood flow is diverted away from your limbs to your core, all of which allows you to hold your breath for longer when, say, swimming 50m under a frozen lake, as Mr Hof is wont to do. Handily for when the daily hunter-gather preset floods us with fight-or-flight hormone adrenaline, the response activates as soon as water covers your visage, overriding the symptoms of a panic attack. This it the one time when a sinking feeling is comforting.

Mr Carney’s odyssey of suffering takes him, incongruously, to Wolverhampton in the UK to compete in Tough Guy, the original obstacle race (and still one of the hardest) that is held, sadistically, in January. Aside from the cold, camaraderie and psychological conditioning that he reports, another upshot of these events is that they reacquaint us with Mother Nature, and she is, well, filthy. Soil is a fertile breeding ground for beneficial bacteria such as mycobacterium vaccae, which not only combats asthma and tuberculosis but also reduces stress and extinguishes inflammation. While eating mud pies or raw meat is ill advised, there’s a groundswell of scientific opinion that our clean-freakiness is contributing to allergies, autoimmune diseases and even coeliac disease. So whether you sign up for a 10-mile sufferfest or dip your toe with what the Japanese call “forest bathing” (walking in the woods, and nicer than ice), embrace the dirt.

**_What Doesn’t Kill Us _(Rodale Books) by Mr Scott Carney is out now **

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