The Iceman's students look wary as they watch him dump bag after bag of ice into the tub of water where they will soon be taking a dip. Under the direction of Iceman" Wim Hof, the group of athletes is going to stay in the water for minutes practising his meditation techniques. Hof, 52, earned his nickname from feats such as remaining in a tank of ice in Hong Kong for almost 2 hours [and] swimming half the length of a football field under a sheet of ice in the Arctic. Hof tells his students meditation in the cold strengthens mind and body. For most people, hypothermia begins shortly after exposure to freezing temperatures without adequate clothing, and it can quickly lead to death. Hof says he can endure cold so well because he has learned to activate parts of his mind beyond the reach of most people's conscious control, and crank up what he calls his "inner thermostat." "I never had a teacher, and I never had lessons, other than hard Nature itself," he says in an interview at his apartment in Amsterdam. "If you do it wrong, it hurts and you take some knocks, and if you do it right, then you really learn." Hof may be able to exercise some influence over other body functions considered involuntary, [and] tells his students at the Rotterdam workshop that viewing mental and physical training as separate may hinder their performance. Hof describes the three main elements in his method as controlled breathing, paying close mental attention to signals coming from the body, and crucially, keeping an open mind.