What Doesn't Kill Us: How Freezing Water, Extreme Altitude, and Environmental Conditioning Will Renew Our Lost Evolutionary Strength

much of the developing world—no longer suffers from diseases of deficiency. Instead we get the diseases of excess. This

Have you ever seen a rabbit go to a pharmacy, a hospital, or a mental asylum?” he asks rhetorically. “They don’t look for medicine, they heal themselves or die. Humans aren’t so simple; they’ve let technology get in the way of who they really are.” It’s an idea that I’ve thought a lot about, and one that doesn’t always sit comfortably. Yes the modern world has its drawbacks, but nature can also be brutal. So I interrupt the budding diatribe. “But rabbits get eaten by wolves,” I say. Hof doesn’t skip a beat at my interjection. “Yes, they know fight and flight. The wolf chases them and they die. But everything dies one day. It is just that in our case we aren’t eaten by wolves. Instead, without predators, we’re being eaten by cancer, by diabetes, and our own immune systems. There’s no wolf to run from, so our bodies eat themselves.

With no challenge to overcome, frontier to press, or threat to flee from, the humans of this millennium are overstuffed, overheated, and understimulated. The

Most people leave Hamilton’s workouts refreshed rather than exhausted.

If we want to become strong, passionate, and motivated, we have to take on seemingly impossible tasks.

Every human alive today lives in a cocoon of consistency: an eternal summer. “We’re overlit, overfed, and overstimulated, and in terms of how long we’ve been on Earth, that’s all new,

the muscles in your feet. Then clench your calves, then thighs. Work the contractions up your body until every part of you is tight from the bottom to the top. Clench your stomach, your chest, fingers, biceps, and jaw. Tighten the muscles behind your ears and imagine all of this pressure that you’ve built up going out the top of your head like you were rolling out pizza dough. Whenever I do this I end up making all sorts of grunting noises and squint my face into awkward contortions. It feels like I’m going to pop. But I never have. Once you finally have to breathe, take in a half lungful of air and hold it for about 10 to 15 seconds. This is the recovery breath, and it feels awesome. Now start over from the beginning. Since your lungs start near empty, it won’t be possible to hold your breath as long as with the basic breathing technique. Aim to increase the amount that you hold your breath with each repetition. When I do it I start with

Ten thousand or more years before that our species migrated between continents on rafts of seaweed and surmounted mountains in little more than animal skins and leather soles. Those ancestors probably didn’t think of themselves as different from the environment at all. They knew what we are learning again today. That we are all just here.