Tai Tuivasa was just a teenager lazing around with friends watching the UFC on television when, together, they created a eureka spark.

“One of my friends said, ‘F**k, these guys are crazy, but I reckon you can give them a hiding,’” Tuivasa recalls. “And I said, ‘I reckon I can, too.’”

That kind of declaration could have easily been dismissed as youthful bravado, but by that time, Tuivasa had already built up a fearsome local reputation. At 17, he was big (6-foot-2 and nearing 300 pounds), he was known to be down for a scrap (he was bestowed the nickname “Bam Bam”), and he’d already shown innate athletic talent, having been signed by the Sydney Roosters of Australia’s professional National Rugby League. Because of that notable accomplishment, his future seemed to be set. Stardom seemed to be in the cards for him. But little by little, as the game’s rules and standards attempted to force him to conform his quirky personality, his love for “footy” had waned.

Team sports were good, but an individual combat sport? As he watched with friends, it all seemed so tempting. And within a few months, he went ghost on the rugby world.

The switch wasn’t made in total haste; by this point, Tuivasa had already boxed and competed in MMA in his spare time, and the individualism of combat competition called to him.

“I grew up in a place where I watched people do what didn’t make them happy,” he says. “I wasn’t going to be like that. And I didn’t have the passion.”

“I grew up in a place where I watched people do what didn’t make them happy. I wasn’t going to be like that.”

His passion was in fighting, something that was ingrained in him from the start. His father Tony grew up boxing and competed professionally but couldn’t seriously pursue the career due in part to his fast-expanding family. Tai grew up with 11 brothers and sisters, and says that at times, he had “20-something” people living with him in his Mount Druitt home.

“It was hard but that’s how it was, just another day in the ‘hood,” he says. “As a kid we didn’t have much. I lived in a slummy area and we never had much money. We had to fight just to get by, but I loved the challenge of fighting.”

There were plenty of opportunities for him to meet that challenge. Growing up an Aboriginal with Samoan heritage, Tuivasa found many places where he was told he didn’t belong, that he was different. From those experiences, he found out early on that he didn’t mind fighting — that he even liked it.

“We were just street kids,” Tuivasa says. “It’s what we did. Sometimes fights looked for us. Sometimes they didn’t. But I realized I liked to have a bit of a fight.”

These occasional fisticuffs came in between his other, more serious athletic pursuits. He was a successful state swimmer for a while, following in the steps of his mother. He chased rugby. He played, he says, anything his family could afford.

By the time he was 15 years old, he came to the attention of the National Rugby League’s Penrith Panthers and was signed to their junior squad. His passion for the game, though, didn’t last, having been deflated by the strict standards imposed by the teams and coaches. Within two years, he was gone. Within a year of pursuing MMA though, he gained another big break when his new coach asked him if he was interested in going to New Zealand to spar with legendary heavyweight Mark Hunt.

“I said, ‘F**k, of course, he’s the top dog, he’s the pinnacle,’” Tuivasa says. “The first time I saw him fight, I said to myself, I want to be like this guy, a warrior at his finest. To get the chance to meet him and help him out, I took the opportunity real quick.”

Tuivasa apparently made an immediate impression. Hunt — who has become Tuivasa’s mentor — is on the record saying Tuivasa is the hardest hitter he’s ever experienced. That is no small feat; Hunt has shared a ring or cage with Fedor Emelianenko, Junior dos Santos, Alistair Overeem and Jerome LeBanner, among others. He is as fair a human gauge as exists in this world, making his statement a compliment of the highest order.

“I’m also getting hit back by Mark Hunt,” Tuivasa says with a laugh. “It’s nice to hear but this is is how I look at it: If you can spar with this guy, what the f**k is anyone else going to do to you?”

To date, Tuivasa’s workout room power has certainly translated to a cage. Now 24 years old, he’s 6-0 and no one has yet extended him past the first round. He’s created a couple of highlight-reel finishes, turning out the lights on Brandon Sosoli with a one-shot elbow on the Australian regional scene, and then short-circuiting Rashad Coulter with a flying knee in his UFC debut last November.

Tuivasa makes jokes about these things. He calls himself “fat-guy fast” and “fat fit,” but the truth is he’s a good athlete. He still has work to do on his game but the foundation has been built. His rugby experiences prepared him for the contact and aided his footwork. He has natural power. He has experienced the training regimen of a professional athlete. And perhaps most important of all, he loves the big stage. Against Coulter, he walked to the cage belting out Vanessa Carlton’s 2002 piano-driven pop song “A Thousand Miles.” And the crowd ate it up.

Mark Hunt — who has become Tuivasa’s mentor — is on the record saying Tuivasa is the hard hitter he’s ever experienced. That is no small feat.

“I always come to try to put on a show, that’s for sure,” he says. “When I watch the fights, if they’re boring, I f*cking change the channel. I try to make it entertaining.”

He also has a softer side. Tuivasa volunteers a large amount of time with an elderly and disabled men’s group. He takes them out to the movies or fishing, and he says he gets just as much out of the experience as they do.

There is a depth to it. They discuss life, problems, the world. He soaks up their knowledge and lets it reflect back through his thoughts and actions. Life is short and challenging, and then one day, as he has seen over and over through this group, you are gone. You might as well, as he says, have a real crack at life.

It’s the same attitude he takes with him as he ascends up the heavyweight ladder. The division is desperate for an infusion of youth — the average age of ranked UFC heavyweights is 33.6 — and his energy and charisma can carry him forward quickly, although he says he’s in no rush. He hopes to be knocking on the door of the rankings by the end of 2018, but a win over Cyril Asker at Saturday’s UFC 221 may well put him there ahead of schedule.

“I’m not going to be a d*ckhead and say I’m ready to fight (UFC champion) Stipe (Miocic), but I’m coming,” Tuivasa says. “I’m from a place where people say you’re going to be nothing in this world. We didn’t have much and I was always in and out of trouble. So there’s no pressure in this, no. It’s all motivation. It pushes me, and hopefully I can make it all come true.”