The secrets behind Mr David Goggins’ extraordinary feats.

As inspirational stories go, Mr David Goggins’ is of the very top rank. He’s the only man in US military history to have completed training as a Navy Seal, Army Ranger (training for which is so gruelling that Seals used to get sent there as punishment – he actually applied) and Air Force Tactical Controller. He’s also an elite endurance athlete, having competed in more than 60 ultra-marathons, triathlons and ultra-triathlons, where he regularly placed in the top five and won several, setting course records in the process. He once held the world record for the most pull-ups in 24 hours (4,030) and, after retiring from the military, became a wildland firefighter.

Lest you think him genetically gifted, Mr Goggins dropped out of the Air Force’s Pararescue School after being diagnosed with the trait for sickle cell anemia, a blood disease believed to increase the risk of fatal cardiac arrest mid-exercise. He served four years as a Tactical Controller, then became a civilian pest controller and ballooned to 297 pounds. After catching a TV show about the SEALs, he shed 106 pounds in three months to re-enlist. And he did almost all of the above paragraph with an undiscovered congenital hole in his heart that meant his muscles only received half the necessary oxygen, and which required two surgeries to repair.

As his scarcely believable book, Can’t Hurt Me, recounts, Mr Goggins’ mind has defeated itself (he was scared of heights and water), his body and everything else, including poverty, a physically abusive father and racial prejudice. Deploy his tactics to win the war that all of us wage with our default tendency towards comfort and complacency.

After getting cut from varsity basketball, flunking an aptitude test to get into the Air Force and learning that he wouldn’t graduate without a drastic improvement, Mr Goggins reflected that it was high time he stop letting his difficult circumstances be excuses. That night, he lectured himself in no uncertain terms in the bathroom mirror before shaving his face and head. So began a daily ritual of setting goals – as basic as making his bed, doing the dishes and pulling up his thuggish low-slung trousers – writing them on Post-its and attaching them to what he called his “Accountability Mirror”. Soon, he was hitting the weights at the YMCA before dawn, running after dark and studying around the clock. “The only way we can change is to be real with ourselves,” he writes.

The lesson: whether your goal is professional, personal or sporting, be truthful – unkind, even – about where you’re at. Then break that goal down into small steps so you can move towards it.

Seal training’s diabolical “Hell Week” is 130 hours of unremitting mental and physical purgatory. Mr Goggins submitted himself to it an inconceivable three times, all in a calendar year, having been forced to restart twice after contracting double pneumonia, then fracturing his kneecap. (Both times, he tried to soldier on regardless.) During his third Hell Week, one of his class died; an officer informed the rest: “This is the world you live in.” Mr Goggins was unsympathetically told that his third attempt to finish training would be his last. So when he developed stress fractures in his shins, he taped his feet and ankles and interpreted the pain as proof of his ever-increasing fortitude. Eventually, his instructors omitted him from “beat-downs” because he looked like he was having fun.

The lesson: The difference between quitting or pushing through is almost always mental. Physical training is a perfect way to hone your stress response and ability to shut down self-doubt.

Mr Goggins’ foray into ultra-running came after 19 special operatives, eleven of them Seals, died in Operation Red Wings (dramatised in the film Lone Survivor, starring Mr Mark Wahlberg). To raise money for their children, Mr Goggins resolved to complete the Badwater 135, aka “the world’s toughest foot race”: 217km through Death Valley in July, when it’s the hottest place on earth. The sadistic organiser challenged him to first run 100 miles with three days’ notice and zero training or experience. After 70 miles, Mr Goggins urinated blood and defecated himself. Incredibly, he still finished, on broken feet, by dipping into his “cookie jar” of previous victories: a concept he employs “every time I need a reminder of who I am and what I’m capable of”. Dig deep and you won’t crumble.

The lesson: We all have past accomplishments, however modest, that we can feed off to sustain us when the chips are down. If you haven’t yet quit, that in itself is a good place to start.

Can’t Hurt Me (Lioncrest) by Mr David Goggins is out now

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