To fully understand why Johnson would fight with a broken leg against a former world champion – and then return to his full-time job as a forklift operator without complaint – you first must understand the lengths he went to in high school to continue to wrestle.
The teen-aged Johnson loved wrestling. He was energised by the rush of head-to-head competition and motivated by the seemingly unending drilling in pursuit of perfection.
He was, in many ways, a mummy's boy, fiercely devoted to the woman who had raised him after his father divorced his mother and abandoned the family.
Johnson is now 26 and hasn't spoken to his father. He hasn't, he said, sought him out even though, every now and then, thoughts of his father waft through his head.
"I don't know what I'd say if I met him," Johnson said. "I wouldn't want to be rude, so I just don't look for him. I don't need the grief of asking why he hadn't been around at all. My mother was my mother and my father at the same time. Everything I am and everything I might become is because of her."
His mother, Karen Crowe, wasn't aware he was wrestling. She was highly protective of him and he was fearful she would not approve of his wrestling. He was always on the go, with a job and plenty of things to do, so his absence from home was easily explainable.
His resourcefulness was tested, though, after one tournament when Johnson took a brutal pounding. Both of his eyes were blackened. His collarbone was broken. Every muscle, it seemed, was bruised or aching.
Rather than going home, Johnson chose to spend a couple of days at the home of his long-time best friend in an effort to hide his condition from his mother.
"My best friend, Jordan, I've been with him since we were in second grade, and I stayed at his house and his mom took care of me," Johnson said, chuckling. "I pretty much laid down a day-and-half straight, just watching my buddy play video games.
"When I got home, my mother was like, 'Where have you been?' I go, 'Jordan's house,' and she asked me if I were OK. I didn't want her to see her little baby all beaten up and tell me I couldn't wrestle any more. I've got a pretty good poker face and typically don't show a lot of negative emotion. I just did what I had to do to be able to keep [wrestling]." He laughed heartily at the memory, but it's illustrative of the man he would become as a professional fighter, a blue-collar, never-quit type of guy.
He's now one of the elite mixed martial arts fighters in the world. On September 22, he'll meet Joseph Benavidez at the Air Canada Centre in Toronto in the co-main event of UFC 152 for the inaugural flyweight title.
He's only been a full-time fighter for about a year. During Johnson's training camp for a bantamweight title bout against Dominick Cruz last October, trainer Matt Hume finally convinced Johnson to give up his $10.76-an-hour job as a forklift operator at a paper recycling plant.
Johnson took up MMA around 2006 at the suggestion of ex-UFC light heavyweight Reese Andy. He did so only to stay in shape and for something to do.
He wasn't planning to become professional. He took a few amateur fights and ultimately then turned pro when he realized he could keep his job working 50 hours a week. He wasn't getting rich working for Caraustar, but that $400 or so weekly pay cheque was far more than he'd be getting to fight in those early days.
Even when he reached the UFC, he hung onto his job, needing the security of a full-time pay cheque.
Hume didn't advise him to quit right away, even though he quickly saw Johnson's potential. The UFC didn't even have a flyweight division at the time, and Hume knew as well as anyone the difficulty of staying in the UFC when fighting up a weight class.
But as Johnson continued to improve and started to look like championship material, Hume felt it was time. During his camp for the Cruz fight, Johnson finally quit the forklift job to concentrate on becoming a full-time fighter.
Clearly, it's been the proper decision. Still, Johnson is only a fraction of the fighter that Hume believes he can eventually become.
Hume is one of the sport's most respected trainers and rarely makes boasts or outrageous statements he can't back up. He's convinced that when Johnson finally reaches his peak, there will be no better fighter in the sport.
"It's hard to say [how far Johnson is from his peak now], because martial arts is a lifetime of learning," Hume said. "He's got the talent, he's got the athletic ability to go further than anybody else that's in the sport today."
That is a massive statement by a man not prone to hyperbole. UFC middleweight champion Anderson Silva is generally regarded as the greatest fighter in the sport's history.
Light heavyweight champion Jon Jones is perhaps the most physically gifted champion. Welterweight champion Georges St-Pierre has dominated elite opposition for years.
Hume, though, doesn't back down. Johnson is a magnificent talent with untold potential, he said. If he reaches his peak, he'll be better than anyone, Hume said, including Jones, Silva, St-Pierre and all the rest.
"He's just an incredible athlete," Hume said. "People say, with good reason, that Demetrious is the fastest fighter on the planet. His balance, his athleticism, all those things are amazing. When he adds all the technical things, I'm telling you, he's going to be an incredible fighter."
Johnson's already proven to be an incredible fighter and an even better person. Anyone who knows him raves about the kind of person he has become.
He's not a quitter, as he showed in his win over ex-bantamweight champion Miguel Torres at UFC 130 last year.
Torres is much bigger than Johnson, who was fighting at 135 at a time when he could have easily been making 125.
But Johnson was competitive in the bout from the start. Early in the second round, Torres checked a Johnson kick.
The crunch he heard did not inspire much confidence about the health of his leg – he figured quickly that it was broken – but his first thought wasn't about how to get help and get it treated. It was about how to defeat one of the greatest fighters in the world on one leg.
Johnson had broken his fibula, but went on to win a unanimous decision over Torres that propelled him into the title shot against Cruz. While many felt Torres won, the fact that Johnson was able to fight two rounds on one leg says much about him as a competitor.
"He goes 100 miles an hour the entire time," UFC president Dana White said in tribute to Johnson.
This is a guy who in high school worked the graveyard shift at a Taco Bell. He worked from 6 p.m. to 2 a.m., caught a few hours of sleep and then headed to school. At 2:30 p.m., he went to wrestling practice until 5. He'd return home by 5:30, eat and then head to his job.
Johnson did it because he badly wanted to buy a car. He pushed himself nearly to the brink of exhaustion with his around-the-clock schedule, but he was finally able to buy that 1995 Honda Civic hatchback he wanted and make the car and insurance payments himself.
It's also why he trained for a fight while he was on his honeymoon. He wants to make the best use of each of the day's 24 hours. And with a flyweight title fight looming, the best use of that time was not relaxing on a beach somewhere.
"I'm the kind of guy who likes to be busy," he said. "I have never liked to have things handed to me. I wanted to work for them. Getting something means more to me, I guess, if I bust my butt to get it."
Nothing has been handed to him and he's nearly at the top of his sport. If he ascends to even greater heights, it's because he'll never forget his humble roots.
He quit his job at Hume's recommendation because he wanted to reach for the stars. It wasn't, though, a simple decision.
"I took a leap of faith," he said. "When you want to get anywhere in life, you have to take risks. There's no way I'd be able to afford this house if I were just working at Caraustar. There is no way. There is no way I'd have made the money I've made as a professional fighter if I wouldn't have taken that leap of faith. When you want to reach for big things in life, sometimes you have to take risks. I took a leap of faith because there was a big pot of gold at the end I was shooting for.
"I trusted that my skills could carry me to the highest level. There's still a point you're scared, because MMA is a winning sport. You need to win to keep your job. It's not like the NFL, where you sign a contract and they pay you every week whether the team wins or loses. … When I looked at everything, I knew I had the ability to do some things in this sport, but there were risks involved. I've overcome whatever roadblocks I've had in my life by working as hard as I could, and that's all I'm going to keep doing now."