”Fatigue makes cowards of us all” is one adage that stands strong in the squared circle.

McGregor was crushed by Mayweather, who still prepares the old-school way, including the oldest-school way of all—he puts in his miles…

As the hype-beat of a second fight between Mayweather and McGregor begins, and as their respective promotional machines start their work of building expectations of what could come, which really means disappearing what actually happened in fight one, we must remember this: well before Round 10, when Mayweather finally TKO’d the MMA champ, Conor McGregor was gassed. Forget that McGregor didn’t know how to throw a punch. Forget that McGregor was toyed with throughout the fight—Mayweather never showed fear of this man and could have delivered the knockout blow at any time from Round 3 on. Forget that McGregor didn’t belong anywhere near a boxing ring because his boxing bonafides were nil. All we need to remember is the truth of Conor McGregor stumbling around the ring, huffing and puffing, too weary to lift his hands, too weary to protect his head. Fatigue beat Conor down before Floyd did.

I refused to pay for this fight, which I knew would be a mismatch. And I was glad to see the MMA fighter laid low by a pure, if arrogant, boxer. But what pleased me most was that McGregor, who has the endurance to spout about his new-school training techniques, was crushed by Mayweather, who still prepares the old-school way, including the oldest-school way of all—he puts in his miles. Money May may not run at the traditional crack of dawn, but when his training is done, he’s done his roadwork.

When I used to hang around fighters more, I had one litmus-test question, which, if I were a full-time fight writer and researcher, I could have used (I think) to chart success: How many miles do you run?

Fighters dread getting knocked out—human instinct says stay upright, stay conscious. That’s why the sweet spot of the sweet science is predicated on how to stay conscious, if not hyper-aware, at all times. As one trainer told me at the Thomas Jefferson Rec Center in East Harlem when it housed a boxing ring, when I hit the bags and pads and heard boxing’s maxims as a half-assed student of the game, not as a part-time reporter: No matter what you do, keep your hands in front of your head. As long as you can think, as long as your mind is working, you can defend yourself.

This specific riff on a referee’s pre-fight Protect yourself at all times, bottom-lines boxing. If your brain waves stay circuited, you have a fighting chance.

Yet there’s one glaring exception to this bottom line for professional fighters, who (unlike many amateurs) have learned to control fear and who’ve forged an almost super-human will to take pain, enduring shots to the body that would end every street fight, shots to the face that would force most mortals to wave white flags. A fully-functioning brain doesn’t fully function, even when hands are protecting head, when a fighter’s out of breath. Beyond the physiological need for oxygen to survive, when a fighter tires, the fight is usually done. Fatigue makes cowards of us all is one adage that stands strong in the squared circle.

Lightweight champ Sean O’Grady said he became a true professional when he learned to breathe in the ring. When he earned the self-belief that he could remain relaxed no matter how long a fight lasted, he knew he was ready. O’Grady often did ten-mile runs in preparation for a fight. That kind of mileage breeds breathing-confidence.

Joshua Clottey, a fighter I watched train, ran many miles every day, not just when preparing for a fight. Clottey was a master technician and always in supreme physical condition—I’ve visited enough gyms to recognize gradations of shape, even among professionals. But Clottey often fought safe, and his safety-first approach, which sometimes tipped the balance against him (perhaps most famously in his fight with Miguel Cotto), seemed predicated on reserving strength. Only in the later rounds, when his natural concern of growing weary had dissipated, when he could see the fight’s end and not the fight’s middle, which must look like the longest road without exit signs, did Clottey choose to expend full-throttle energy. Joshua Clottey, with all those miles in his legs, understood (perhaps too well) the devastating and oppressive power of fatigue.

And say what you will about Floyd Mayweather, like Muhammad Ali who did his road work (and his push-ups and sit-ups), Money May never let success shorten the distances he forced himself to run. He’d do eight miles at a pop, sometimes in the desert heat, sometimes at night when the roads were clear and he was awake thinking, not just of money but of his upcoming fight (no matter how much he might protest, I believe Floyd was as concerned with his undefeated legacy as with his millions, which is why his TBE self-publicity campaign was more about 50 and 0 than getting the biggest bucks for his bang). Floyd Mayweather, the pugilist, ensured he’d remain undefeated (and un-tired) by running long runs.

With few exceptions, the fighters who achieve most are those who pay deference to fatigue by doing distance roadwork, never skimping miles, because they understand that without an oxygen-rich will, founded on having enough breath to keep going, skills don’t matter.

It’s an obvious equation: the fighter who tires least usually wins. But just as there are right ways to make weight, there are right ways to run and the right way, time-tested, says length matters. While some modern trainers sporting physical fitness degrees concoct regimens that favor speed-bursts, I remain unconvinced that there’s a substitute for old-school roadwork.

A list of boxers who ran/run long miles and achieved/are achieving pinnacle stardom (like Ali and Mayweather) highlights the efficacy of multi-mile runs:

Old-school Floyd Patterson ran marathons.

Sugar Ray Leonard ran five miles a day while training and still calls himself a runner.

Oscar De La Hoya was an hour-a-day runner, rumored to do ten miles at six-minute-per pace.

Joe Calzaghe, always supremely fit and supremely busy in the ring, did six miles a day, at least.

Roy Jones, who relied as much on leg speed as his fast hands, never skipped his five-mile-a-day routine.

Tim Bradley, who trained desert-storm style in Coachella-Valley heat, did eight-mile runs.

Vasyl Lomachenko runs up to thirteen miles at a stretch, half-marathon distance, during training camps.

Gennady Golovkin runs for an hour and a half through Big Bear’s high-altitude mountains while prepping for a fight. (Triple G’s the most heavy-handed puncher on this list. The rest usually broke/break their opponents down over rounds, which requires long-range, not short-term stamina.)

Errol Spence, a budding superstar, does five to six miles per day of old-school roadwork.

When prepping for a marathon, trainers tell you to put miles in your legs, to stockpile miles like it’s money in the bank. The pace, they believe, is less important than the distance. We’ve all seen pre-fight footage of our favorite A-list boxers running empty roads—some desert-flat, some mountain-steep. They’re not running ultra-fast, they’re breathing fairly comfortably, but those roads, long and lonely, speak to multi-mile runs meant to build confidence against fatigue, meant to scare away, when the fight becomes exhausting, those cowardly doubts.

Perhaps one fictional example about roadwork stands best for the non-fictional fighters who put in their requisite long-distance roadwork. One of the few great boxing novels, The Professional by W.C. Heinz, tracks the preparation of a middleweight named Eddie Brown. Only the novel’s final pages are about the big fight. The bulk of the book is about the getting-ready. Here’s an exchange between Eddie Brown’s trainer Johnny Jay and Eddie Brown’s manager Barnum as their charge, running alongside some other fighters, prepares for his title shot:

“Eddie’ll make ‘em run,” Jay said. “In a few days Eddie’ll get his legs under him and they’ll have to run to keep up with him.”

“Eddie’s a good boy,” Barnum said.

“People think a fight is won in the ring,” Jay said to me. “You know where a fight is won? Right here. Right here on the road and in the gym.”

The “me” is the narrator, a sportswriter, probably a fictional stand-in for the talented W.C. Heinz. The lesson of this exchange is clear. Eddie Brown loses his big fight, but what gets him to the top of his profession, what makes him a “good boy” in the eyes of his veteran fight manager, what impresses his seasoned and wise trainer, is that Eddie Brown remains a disciplined runner, mentally strong enough to put in the necessary consistent roadwork. Of course, even the most in-shape fighters can get KO’d by superior opposition or a punch on the button, but few fighters, especially fighters who are more human than super-human, are able to build their careers and reach title-fight heights without the unique fitness that comes from long runs, without the legs and the breath to take it and take it and take it some more.

Muhammad Ali, whose poetry is overrated, but who had true moments of eloquence when he wasn’t forcing rhymes, echoed Heinz’s words. Here’s one of Ali’s best non-poetry lines, “The fight is won or lost far away from witnesses—behind the lines, in the gym, and out there on the road, long before I dance under those lights.”

That’s a beautiful line said beautifully. And Muhammad Ali’s words point to the foundation of Muhammad Ali’s success. He was super-human as a fighter, blessed with speed in his hands and grace in his feet; Ali could have coasted far on talent alone. But Muhammad Ali reached close to real TBE-status because he didn’t simply rely on his gifts. He worked. He stayed disciplined far away from witnesses. And he ran. He put in those long miles out there on the road.

Adam Berlin is the author of four novels, including the boxing novel Both Members of the Club (Texas A&M University Consortium Press/winner of the Clay Reynolds Novella Prize) and Belmondo Style (St. Martin’s Press/winner of the Publishing Triangle’s Ferro-Grumley Award), and the poetry collection The Standing Eight. He teaches writing at John Jay College/CUNY and edits the litmag J Journal: New Writing on Justice. For more, please visit adamberlin.com.