Finland’s Arctic circle might not seem like a great place to run a marathon barefoot and in shorts—unless you’re Wim Hof. Hof, better known as “The Iceman,” has attained roughly two dozen world records by completing marvellous feats of physical endurance in conditions that would kill others. Yet even he was understandably nervous the night before his 26-mile jaunt at -4 degrees Fahrenheit.

“What did I get myself into?” he recalls thinking. But from the moment his bare toes hit the snow, he began to feel “surprisingly good.”

MRI scans reveal that Wim Hof artificially induces a stress response in his brain. “By accident or by luck he found a hack into the physiological system,” they say.

How? Well, you know what we think. The placebo effect in action once more!