For each of us, there is a point beyond which physical exertion becomes something else. This is not a fixed point, as it changes with your level of fitness; the fitter you are, the harder you must work to get there. It is more like a receding mountain, out there in the distance, surrounded by fog. Let’s call it the Breaking Point.

Note that this is not the same as “hitting the wall” or “bonking,” a sharp decrease in energy that often leads to quitting, familiar to marathoners and other endurance athletes. Bonking usually happens when your body switches from using stored carbohydrates for energy and starts burning fat instead, but trained athletes, especially ultramarathoners, know how to get around it, through a combination of advance training and nutrition during the exercise.

Still, no amount of training and in-race nutrition will help you against the Breaking Point. It may not happen always, and elite athletes are much more immune to it due to their intense training. (Some professional marathoners and ultramarathoners run 120 to 150 miles a week. Most of us don’t have the time to do it . . . or the body.)

But the Breaking Point is there for everyone, novice or world-champion marathoner alike. And if you are persistent and fortunate enough to hit it, things change for you in irreversible ways. So much so that, to some of us, its pursuit becomes an ongoing quest, one that renews itself with every new attempt.

Most people, and I mean the vast majority, don’t relate. Even those who exercise regularly slow down when their hearts pound too fast and their bodies start to hurt. Or they might tolerate a low level of pain, but don’t want to go beyond it. And that’s perfectly okay, as long as your goal in exercising is to achieve a certain level of fitness.

But what if you want to go further, pushing your body beyond mere exercising? What if you want to train yourself to “become comfortable with being uncomfortable,” as many in the extreme endurance-sports community like to say? Opposite to bonking, you don’t stop at the Breaking Point but keep pushing through it, stepping into unknown realms of endurance and mindfulness.

A few years ago, I’d say that this is all nonsense. What’s the point? Why would you subject yourself to running 50 miles on mountain trails, or do an Iron Man, or swim for miles in cold ocean water? Why would you register to run a Spartan Beast or a Tough Mudder, grueling obstacle course races where you not just must deal with tough hilly terrain but also climb ropes, carry sandbags uphill, crawl in mud under barbed wire, conquer eight-foot walls, swim in frigid waters, and other similarly evil challenges?

“You will know at the finish line,” says the Spartan race motto. And unless you push yourself to get there, you can’t understand what’s all about.

The Marathon Monks

I’ve been doing some of these things for seven years now. And I’ve noticed that it is impossible to explain in words why this is all so meaningful to some of us, to the point of being life-changing. When I tell someone that I just did a 50-mile race in the Quebec wilderness or over the French Alps, they look at me as if I were nuts. “How long did it take you?” they ask. When I say, “Oh, about 13 hours or so,” they just shake their heads. “What an idiot,” they are thinking.

Clearly, they don’t understand the significance of the Breaking Point. You can’t, unless you experience it. Here is an extreme example.

In the outskirts of Kyoto, on Mount Hiei, there is a sect of Tendai Buddhist monks that use the Breaking Point as a gateway to enlightenment. Known as the Marathon Monks, their physical feats are unparalleled in the world. (You can watch a documentary here).

A sacred site on the mountain.

Not all Tendai monks are allowed to attempt the ultimate challenge, the Sennichi Kaihogyo, the Thousand-Day Challenge, a seven-year circuit where they must walk-run a distance equivalent to circling the globe, while worshipping the more than 250 sacred sites in and around Mount Hiei: waterfalls, springs, sacred trees, bubbling streams, stone images, temples. The mountain is their temple, the sacred body of the Buddha.

There are two circuits, the longer one covering 28,938 miles, and the “shorter” one covering 24,004 miles. The yearly breakdown is unimaginably difficult: From year one to three they must run for 100 consecutive days, covering either 19 or 25 miles per day. For years four and five, they must run for two blocks of 100 consecutive days, covering the same distances. For year six, they run the longer distance of 37 miles for 100 consecutive days. Finally, on year seven, they first run 52 miles for 100 days and then another 19 or 25 for 100 days more. They start at two in the morning, wearing robes and straw sandals. Their diet is mostly miso soup and rice. Those who complete the challenge are considered living Buddhas, enlightened saints, worshipped as living gods.

I visited Mt. Hiei with my wife in January 2017. As we are both ultrarunners, we wanted to meet the one living monk who had accomplished the challenge and, while there, run on the same trails they do. Heavy snowfall had made the mountain practically empty of the usual tourists. It was just us, the monks, and very few devout followers. In the winter, the spectacular complex of centuries-old temples, nested on the mountaintop, and its surroundings can only be reached by cable car. The journey was magical. Each foot that we climbed took us farther into a different realm, where time flowed at a lazy pace. Even snowflakes seemed to engage in exploratory wandering before settling on the ground.

We got to our room, changed into running clothes and went out, map in hand. Hilly, snowy conditions are tough on you, and after eight or nine miles we were far away and tired. Still, we took an offshoot narrow trail and kept going, surrounded by pine trees and solemn silence. As we moved, we noticed small monuments made of cut stone along the trail. Some of these marked the remains of monks who failed to complete the challenge. Up to the late nineteenth century, those who didn’t finish had to kill themselves. Talk about pressure to finish.

You don’t have to be a Tendai monk to experience the Breaking Point. If you push yourself hard enough, you may eventually reach it. Your body will be in agonizing pain, begging you to stop moving. Dark thoughts may invade your mind, telling you that you are insane, that this is all useless, that you will hurt yourself, cause permanent damage to your body.

Gleiser on Mt. Hiei

What would a Tendai monk do? He would pray harder, shake off the dark thoughts, and move forward with discipline and, above all, with gratitude. He would know that to be out in the woods, embracing the beauty, worshipping Nature with body and spirit, is a privilege. And that to do it beyond the Breaking Point is the purest form of devotion, when all the fake layers of your inner self are removed—and only your true essence remains.

When the body crumbles, and it eventually does, what’s left is the spirit. In the West, people prefer to use words like “grit,” “perseverance,” or “determination,” but it is all spirit-driven. Physical pain opens the doorway to a different state of being, where you are exposed to your very core. If you find the strength to push through it—and we are much more powerful and resilient than we think we are—you will emerge a different person, more intimate with who you are than you thought possible.

In the ultrarunning community, people like to say that the hardest few inches to conquer in a long race are those between your ears. As we approach the Breaking Point, our minds interfere and start to play tricks, trapping us into bottomless wells of unhappiness. This is where we dig a little deeper, and find the will to push forward, knowing that the pain will eventually go away.

And as you do it, you feel a strange sort of liberation, a kind of lightness that, in some of us, brings forth an explosive emotional release. At that moment, the pain disappears, the face breaks into a wide smile, and the eyes brighten up. You have gone beyond the Breaking Point and you will never be the same.

Until, of course, you set yourself a new challenge, and face a different mountain looming in the distance and you can’t wait to run toward it with a smiling heart.

It goes without saying that trying to reach this Breaking Point requires time and great effort. Always check with your physician before beginning any kind of endurance training/running. 

Gleiser is a professor of natural philosophy, physics and astronomy at Dartmouth College.