In 1977, a near-death experience in the boxing ring forced Olympic gold medallist and world heavyweight champion George Foreman to retire from the sport.

To get where he was at that point in his career, Foreman had overcome a troubled childhood in Houston, Texas, marked by poverty to train his way up from amateur to professional boxer, along the way becoming a formidable fighter, knocking out some of the world’s best boxers – and famously being beaten by Muhammad Ali in 1974’s Rumble in the Jungle.

However, after losing an intense fight against Jimmy Young in 1977, Foreman underwent a profound emotional and spiritual rebirth – a moment which he described as “an experience with death” – which helped him find God.

“I had that (near-death) experience in a dressing room. I had a vision I was dead and alive again. And I was hopeless – the most hopeless thing I’ve ever been in; the most depressing, scary thing. I was gone, and out of nowhere I just got mad and said: ‘I don’t care if this is death, I still believe there is a god’,” says Foreman, now 74, of the experience.

“And when I said that, I was snatched out of this hopelessness and I was alive again in the dressing room. They had literally picked me up off the floor… I started screaming it.

“And until this day I still scream Jesus Christ has come alive in me.”

For the next 10 years, the boxer stopped fighting and dedicated his life to God, becoming an ordained minister.

But it was not over for Foreman’s boxing career: after 10 years away from the ring, he announced a comeback in 1987.

George Foreman – nicknamed Big George – would then go on to become the oldest world heavyweight champion in history at 46 years and 169 days old.

It is a truly incredible story, and one that is ripe for the telling on the big screen.

Khris Davis – best known for roles in Judas And The Black Messiah and Space Jam: A New Legacy – will play the champion boxer in George Tillman Jr’s Big George Foreman, a biographical sports drama telling the tale of Foreman’s life from childhood to championship.

The star says he was initially intrigued by “all the things that I didn’t know” about Foreman’s story when he took on the role.

“I think that will be true for a lot of people – they are going to learn a lot of things about Mr Foreman that they did not know,” he continues.

“What was really intriguing to me when I read the script, and when I read his autobiography, was just how gentle he was in his heart.

“That was easy to miss because of his public persona. Even when he was a pastor making his comeback, you didn’t get a chance to really see inside, and I think that’s what interested me the most – his internal gentleness.”

“Going into it, I knew the ‘George Foreman Grill guy’,” Davis continues.

“I knew that he was a boxer and had seen some of his fights before, but I didn’t know much about his earlier boxing career. I had no clue about his transition into faith.

“When I learned about these things, he became a lot more interesting to me as a person. Where did all this come from? How did he get from here to there, to there?

“I also wanted to see what he was like personally, so I went down and spent about three days talking to him in Houston. That was the key, because doing my research, as I said, all I had were interviews. He was either being interviewed as the heavyweight champion, or the Olympic champion, or ‘the comeback guy.’

“There were all these presentational behaviours, but it wasn’t the personal behaviour that I needed to tell his story.”

“I always said if there’s ever a movie done about me, I would hope it would be a real actor. Not some ‘celebrity’. Someone who could really act. And boy, they got an actor for this,” says Foreman of watching Davis play him on screen.

“I was so impressed with him. I met him a couple of times. He took it on and he was George Foreman as far as I’m concerned. I am so impressed with Khris Davis.”

Transforming into a legendary boxer is no mean feat, and not only did Davis have to train relentlessly and learn to box, but he also had to adapt his body to portray Foreman during his spiritual transformation, gaining nearly 22.5 kilograms under the supervision of a dietician during a six-week break in filming.

“The first transformation was just getting into fight shape. Darrell Foster was my fight coach and he treated it like it was a fight camp,” says Davis.

“The whole concept was, ‘you’re not training for a movie, you’re training for a heavyweight fight’. We had a bunch of fighters who would come in for the various fights in the film (including Carlos Takam, who plays Joe Frazier) and I would have to spar and train with all of them.”

The fight training was, of course, essential, particularly because the fight choreography was designed to be as true to the real-life fights as possible.

“We were very specific about what punches were thrown, where they’re thrown, and where they’re thrown in the ring – you know, what side of the ring we’re on,” says Davis.

“Our goal was to emulate the fights as specifically as possible so that if you were to run the fight video next to our footage it was the same.”

At the heart of Big George Foreman is a story of spirituality, of finding oneself, and realising one’s purpose in life, which is something Davis took to heart during the production.

“I really feel that in anything you do, when (you) really find yourself and you’re being honest with yourself on a deeply spiritual level, it’s the best thing you can do for your life,” he says.

“What does it matter to have the millions that he made from boxing when he leaves this world? It means nothing. You can’t take that with you.

“What matters is what we do with the time we have now. What better way than to live your fullest, your boldest, most beautiful and honest self?

“He was living his most honest existence and I think that that’s beautiful.”

Big George Foreman is in cinemas now.