More on this book
Community
Kindle Notes & Highlights
Read between
September 22 - October 8, 2025
“And in the military you’re always carrying weight. No matter what. Always,” said McCarthy. “Rucking is the foundational skill of being a Special Forces soldier. Any soldier for that matter.”
“The Greeks, Roman legions, etc., they all trained similarly: load a rucksack and head out into the woods. US Special Forces trains this way.
Rucking is essential to military might. So the US government has poured millions of dollars into studying the act. McCarthy has read all this research and become something of a rucking-obsessed lay scientist.
“Rucking is strength and cardio in one,” McCarthy said. “It’s cardio for the person who hates running, and strength work for the person who hates lifting.”
“So then what kind of body type does it build?” I asked. “We call it super medium,” he said. “Just think of Special Forces guys. We can’t be too thin, but we also can’t be too muscular.
It also suggests that packing 100 pounds of caribou across the steepest pitches of the tundra burns between 1,850 and 2,150 an hour.
McCarthy founded GORUCK after exiting the military. “Special Forces guys get all the best gear,” he told me, pulling off his ruck. “You usually can’t ruck with over thirty-five pounds in a regular backpack.
So he did. Took him about three years to develop the first GORUCK bag. It was a black, made-in-America, 26-liter ruck that could hold more weight than a person could ever carry in it.
he developed this far-out idea to get the word out about his company. His business smarts were novice, he said, “but I knew how to do military stuff.”
He called it the GORUCK Challenge. With no less than 35 pounds in their rucks, people would as a team ruck for 12 hours across 15 to 20 miles. Along the way they’d complete group challenges assigned to them by McCarthy.
“If you can consciously put yourself through physical discomfort and understand the higher purpose of it, the ‘why,’ the mental calluses that come along with that create what is called the Well of Fortitude,”
Not because we were special, supersmart, or had access to family money. But rather, we knew our higher purpose and were able to draw on the Well of Fortitude we built on challenging missions in the military to buffer stress, work harder, and simply endure.”
There is, in fact, no such thing as “too much” exercise.
The Johns Hopkins scientists found that people who exercised more than three to five times the amount the government recommends were radically less likely to die.
Many people think that too much exercise can cause heart attacks. But there was also no excess risk posed by exercising even ten times the amount the government recommends, equivalent to 25 hours a week. The Hadza exercise about that much and show “no evidence of risk factors for cardiovascular disease,” wrote Raichlen in a study.
Meanwhile, a swell of exercise evidence is causing more doctors to believe that getting closer to our ancestral activity trends is not only a hedge against sickness but also a cure for it.
“Endurance exercise is not muscle building, and it probably isn’t even muscle maintaining,”
“This is why we recommended in addition to a hundred and fifty minutes a week of endurance exercise that people also do resistance exercise to build and maintain muscle mass.”
“Rucking is particularly great for women for this reason,” said Emily McCarthy, Jason’s wife, who was also at dinner at the Pollaks’. She’s a former CIA operative who now co-runs GORUCK. “You can build strength without having to go lift at a gym.”
Running was the top offender. It caused six times more injuries than rucking.
Outdoor physical activity with people—that’s foundational. That’s what Homo sapiens evolved to do, and it makes us happy.”
Endurance coaches since the 1960s have looked for a competitive edge by having their athletes “train high, race low,” which ramps up oxygen-carrying red blood cell counts.
But the Sports Medicine research team found that altitude training does far more than that. It also leads to changes in mitochondria, which make our muscles more efficient, and improves how we buffer exercise-induced acids, allowing us to go harder longer.
The majority of Icelanders come from a single family tree. It’s so common for Icelanders to have unknown cousins that the government created a genealogical dating app so people can avoid familial hookups.
Iceland’s crucible of discomfort and disasters may have culled the herd. Natural selection suggests the people who couldn’t hack it likely perished. Those with a high discomfort tolerance probably thrived.
The result is that Icelanders may have buried within their genetic code a harder-to-kill gene, one that explains their longevity. If Stefansson can isolate this theoretical gene or set of genes, perhaps he and his team can figure out a way to bring it to the masses.
Marcus Elliott told me that a critical benefit of misogi is what he called “creating impressions in your scrapbook.” “If you’re seeing and doing all the same things over and over, your scrapbook looks pretty empty when you take inventory of your life,”
we need to do more novel things to start creating more impressions in our scrapbooks, so we don’t feel like the years are flying by.
