Having a ripped physique isn’t a prerequisite for actors starring in Hollywood’s biggest films, but it often helps. That’s especially true when the roles are as physically demanding as Jack O’Connell‘s have been. The 35-year-old’s filmography includes playing military personnel on a number of occasions, a vampire in Sinners, and the main antagonist for 28 Years Later: The Bone Temple.
Such a career has required O’Connell to pay particular attention to his fitness. But, despite such taxing roles, the British actor doesn’t actually enjoy traditional weight training or specific cardio to get his body in shape.
Disguising Movement As Fitness
O’Connell admits that he simply doesn’t enjoy building muscle with heavy weights. Nor does he like going for a run. Rather, he prefers specific exercise under the guise of playing sport to keep him interested and on top of his fitness, even when he is required to match the vision of certain aesthetics.
‘I can’t really get down with traditional workouts, like a lot of weightlifting,’ he told Men’s Journal. ‘I have to be punching something or kicking a football. Otherwise, it can just feel a little pointless. Perhaps that’s more of a mindset thing on my end, but I just don’t see the point of it. I find the combination of boxing and playing football is a great combination for me. It keeps my mind fit. It keeps my body fit. I fucking hate cardio, so I need to have it disguised.’
Gareth Cattermole
In the Gym – But Sparring, Not Lifting
O’Connell’s footballing and boxing childhood has served him well. Starting kickboxing aged 11 provided him with invaluable experience for when he played a bareknuckle fighter in the 2019 film, Jungleland, alongside Charlie Hunnam. O’Connell treated preparations for the film like a training camp, sparring at both Westside Boxing in London and then Brighton’s Boston Boxing and Fitness. He even sought advice from Olympic boxer Sandy Ryan, who fine-tuned his movement patterns.
‘The physique I ended up with by the time we started filming was the one I had after focusing purely on my boxing,’ he explained. ‘After a proper training period. I wasn’t going in there trying to look particularly pumped or busting out of my shirt. I was going into this movie wanting to look like a fighter.’ Boxing is a sport he credits profusely for helping mould and develop him when younger, too.
‘I started kickboxing when I was 11 years old, which I feel like is a good age to start,’ he added. ‘It may be a little late if you want to compete, but you’re still flexible and mouldable. The movements can come a little easier when you have that youth on your side. From there, I started focusing more on boxing and striking quickly. I really believe in the science of boxing.
‘I don’t find it to be a brutal sport. There are brutal consequences, sure, but at its core it’s the purest of contests between two individuals. It all starts in that gym, and that’s where a lot of those fights are won. That fascinates me. What I learn from boxing is much more than just what I learn in the ring.’
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While O’Connell had continued boxing throughout his teenage and adult years, he faced an altogether different proposition in getting ready to play Louis Zamperini for 2014 film, Unbroken. Zamperini competed for the United States in the 1936 Olympics in Berlin in the 5000m, but, during World War II, was taken as a prisoner of war in Japan.
Angelina Jolie, who directed the film, wanted someone ‘with a lean, athletic, runners build, or someone who is willing to change their physicality for the role’. She opted for O’Connell, who had an extremely tight turnaround to get Zamperini-ready. The then 22-year-old had just 18 days to prepare for the role, which meant four or five-hour training days to build up his core strength and aerobic capacity, all while losing as much weight as possible to match the aesthetic of an undernourished middle-distance runner.
‘I knew straight away nutrition was going to be first and foremost,’ Greg Smith, O’Connell’s trainer for the film, said. ‘We had to get him up to speed with a proper diet. Training-wise, we avoided too many heavy weights – because that would have caused injury – and focused instead on his core and endurance.’
The training also extended to matching Zamperini’s unique running style. O’Connell said the American’s hips dislocated with each stride, making it a key area of focus for him in the short time he had to prepare. ‘While training, while working on my stamina, after those sessions, we’d spend a little time literally stretching,’ O’Connell told Runner’s World, per Bring Back the Mile.
‘I’d have this pretty weighty PT teacher bearing down, stretching my legs, as it were, and that was just to widen my stride some. But no, other than that I think I had a head start just because I used to play a lot of football growing up. And, yeah, in between seasons when it was no longer possible to play football I’d be on the track sprinting. So I was more of a sprinter than long distance [runner].’
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Ryan is a Senior Writer at Men’s Health UK with a passion for storytelling, health and fitness. Having graduated from Cardiff University in 2020, and later obtaining his NCTJ qualification, Ryan started his career as a Trainee News Writer for sports titles Golf Monthly, Cycling Weekly and Rugby World before progressing to Staff Writer and subsequently Senior Writer with football magazine FourFourTwo.
During his two-and-a-half years there he wrote news stories for the website and features for the magazine, while he also interviewed names such as Les Ferdinand, Ally McCoist, Jamie Redknapp and Antonio Rudiger, among many others. His standout memory, though, came when getting the opportunity to speak to then-Plymouth Argyle manager Steven Schumacher as the club won League One in 2023.
Having grown up a keen footballer and playing for his boyhood side until the age of 16, Ryan got the opportunity to represent Northern Ireland national futsal team eight times, scoring three goals against England, Scotland and Gibraltar. Now past his peak, Ryan prefers to mix weightlifting with running – he achieved a marathon PB of 3:31:49 at Manchester in April 2025, but credits the heat for failing to get below the coveted 3:30 mark…
You can follow Ryan on Instagram @ryan.dabbs or on X @ryandabbs_
