Here's What It's Like to Fight Charlie Hunnam

We start a 30-minute warmup with some easy running, but soon we're doing high-knees, butt kicks, and jumping jacks. Next we're on the mat doing crunches, side-to-sides, leg raises, pushups, and pullups. Hunnam hops on the monkey bars and swings to the end. Sweat spatters on the mat. He does another round of bars, and then another. Later I learn that part of his regular routine includes running 5 miles and doing 300 pushups and 100 pullups. He's ready for American Ninja Warrior. This training session will be intense.

That Hunnam is fastidious about fitness is no surprise. He has to be fit to meet the physical demands of the roles he's drawn to—"muscular male narratives." Fresh off Sons of Anarchy, he switched focus to the big screen, working back-to-back on three movies over the past two years. The biggest is King Arthur: Legend of the Sword, directed by Guy Ritchie (opening in May). He also stars in The Lost City of Z (April 21), about an explorer who disappeared in the Amazon in 1925, and Papillon, a remake of the 1973 Steve McQueen flick (later this year).

But there's more to his motivation to exercise than the desire to look good. "I'm interested in having a high fitness level across the board," he says. "Running, swimming, jumping rope, hiking, jiu-jitsu—I try to do it all. I also try to make love as often as I can. That's an important part of fitness. There's no reason you can't be active at 70. I want to run up mountains at that age."

The learning curve in our jiu-jitsu class is steep. In the first segment, the sensei teaches new moves, starting with arm bars and moving on to choke holds. I'm kneeling on the mat and Hunnam's arm is wrapped around my throat. The pressure on my neck is firm, but I feel strangely safe with him. He's strong but displays precise control and even a lightness of touch. Although brutal, there is an art to cutting off someone's air supply. I double-tap his arm to signal submission. The sensei, Rigan Machado, an eighth-degree black belt member of Brazilian jiu-jitsu's founding Gracie family, says Hunnam is a perfectionist—something I experience firsthand as we practice again and again and Hunnam fine-tunes his chokes. Nothing grounds you in the present more than being unable to breathe. Jiu-jitsu training demands focus and discipline.

That fortitude was tested during King Arthur. To prepare, Hunnam "worked out like a motherfucker." He packed on 20 pounds of muscle by strength training and spent hours learning sword fighting and boxing. The movie's five-minute final fight scene took five days to shoot, filming from 7 a.m. to 6 p.m. "It's not even as much the physical benefit of training; it's the mental," he says. "When you're training every day in a combat discipline, it just gives you that eye of the tiger. Then if someone acts aggressively toward you, I can run all the scenarios through my head—you know, like I'm going to step to the side and put an elbow through your face."

Hunnam sought to reimagine the noble action hero with Ritchie, himself a black belt in BJJ. "We wanted to do something a little rougher around the edges while still dealing with the rich Arthurian mythology," Hunnam says.

After King Arthur, Hunnam had 10 days off. Then he lost nearly 40 pounds in eight weeks playing his next role—Colonel Percy Fawcett, an obsessive British explorer, in The Lost City of Z. Hunnam eliminated dairy, carbs, and sugar. Then he went vegan. The shoot was in humid 100-degree weather off the grid in the Colombian jungle. Hunnam says the biggest hardship was the isolation. He talked to no one off the set, not even his girlfriend, for four months.

"People are all like, 'that's so Method of you.' Maybe it is, but I was worried about the emotional breadth of what I had to portray. I had to access that on a day-to-day basis, so I put myself in the position of living it. I felt the fear, the loneliness." Insects attacked constantly; one even burrowed in his ear. A lightning strike knocked Hunnam off his feet. The movie was shot in sequence, and by the end everyone was a little crazy, says James Gray, the film's director. "Charlie was starving and unhappy. You can see the hopelessness in his eyes. But he never missed a beat. He listens, acts, and then reacts.

"The body transformations continued with Papillon, the most recent movie he filmed. He'd regained some weight and had to lose 30 pounds. "My body was reluctant to drop the weight again," he says. He used the same vegan diet and stole a vice from his character, a felon-turned-prison-escapee: cigarettes. Hunnam puffed "like a madman" and sustained himself on coffee and nicotine for three months. "My body was a mess," he says. "It's not easy to quit smoking." He's currently using e-cigarettes to transition off.

One vice he did quit was smoking weed. He would burn through an ounce a week, but stopped in his early 30s. "In those stupid ways that we identify with ourselves, I felt like I was a Rasta," he says. "I was sort of proud at my enormous ability to smoke pot and function. But I realized I didn't want to spend my life stoned.

"Right now, Hunnam is clearheaded and energetic. We're practicing moves he knows. We stand on the mats, and he teaches me how to do a two-legged takedown. "If you find yourself on the street and someone wants to take you on, you come in and take them off guard," he says. "So if I throw a punch at you, you dodge it. The minute you feel them stalling, step in, put your shoulder into it, and sweep the legs!" We shadowbox for a moment, and then I plunge in. My head and shoulder are pressed against his hip, my arms clenched around his torso. His feet go up in the air, and in one swoop, I knock him hard to the mat. "Niiiice! Just give me a little bit more push!" he yells. I try again and slam him roughly down—seven more times. "You got it. Ohhhh, now I'm in trouble!" He seems to genuinely love practice and learning.

After class we relocate to a restaurant, but the focus stays on fighting and learning. Hunnam tells me about his childhood near Newcastle, in northern England. "It's a violent place. Kids messed each other up pretty good. I was able-bodied and a target and was always having to fight," he says. He liked painting, photography, and playing rugby and had a lot of friends.

When he was 12, his mother moved him and his brother to a small town in Wales. (His parents had divorced when he was 2.) Hunnam felt like an outcast. He spent all his time alone and had a "fuck it" mentality, watching movies like John Boorman's Excalibur over and over. His father, a scrap metal dealer with whom he'd stayed close, passed away four years ago. But he believes he's still with his dad in spirit. "My dad was one of the toughest savage dudes I ever met. In a way, I feel like I have been playing my father a lot in my career," he says.

Hunnam arrived in Los Angeles at 18 "with no education and nothing but an abstract dream and steadfast determination to become an actor." He scored TV and modeling gigs that led to Sons of Anarchy, which he describes as his Ivy League education. "You work so rapidly and have to solve problems on a daily basis, which sharpens your emotional toolbox." The grind strengthened his self-belief, and he embraces it in other ways too. He wants to be fluent in Spanish, so he's taking lessons. He's an avid cook and watches tutorials. And he's determined to earn a black belt in BJJ by the time he is 45 years old.

But Hunnam says he doesn't want a fancy lifestyle (he drove the same beat-up Cadillac for 14 years) and isn't fueled by fame ("It was Socrates or one of those old bastards who said, 'Fame is the perfume of heroic deeds.' It means nothing"). He says he dreams of wandering the wilderness and living off the land with his girlfriend of 11 years. When she was cyberbullied last year, he released a video telling the perpetrators to knock it off. "The way I grew up, if you want to talk shit, talk shit to someone's face and be prepared to fight." He sees social media dividing society, and he despairs. Sometimes after a shoot, he reenters the world disconnected and feeling low.

He combats those feelings with exercise. "We are supposed to be very active animals. It's our DNA." Hunnam derives emotional stability and clarity from his fitness. "Sweating is how I change my oil every day. I just feel happier, more positive, energized, and disciplined if I work out." Ultimately, he says, "I train a lot every day because I'm fucking crazy."

Check out the April issue of Men's Health for more with Charlie Hunnam.