Josh O'Connor has put his body through a series of physical transformations in recent years. From portraying a professional tennis player and a former boxer to an underfed ex-prisoner, the 36-year-old has repeatedly adapted his physique to suit the demands of a role.
What's perhaps most surprising is that, prior to filming Challengers in 2023, O'Connor had never lifted weights.
While his latest film, Disclosure Day, sees him play a cybersecurity expert rather than an athlete, several of his recent roles have required significant physical preparation. For Challengers, that meant spending months developing both his tennis skills and athleticism to convincingly portray the arrogant and intensely competitive Patrick Zweig.
How Josh O'Connor Transformed His Body for Challengers
‘One thing that definitely helped: I’d never spent time in a gym in my life,’ O'Connor told Vanity Fair.
That quickly changed. According to co-star Mike Faist, O'Connor gained close to 5kg while preparing for the role.
‘When I went over to Boston to do this film, Luca [Guadagnino, director] was like, “We’re in the gym”,’ O'Connor recalled. ‘We did three or four weeks of: two hours in the morning, tennis; two hours gym; rehearsal every day.
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‘I was forced into going to the gym. There was no option. And apart from the fact that I felt amazing, I suddenly had all this regret from when I was a kid – if only I’d discovered the gym earlier, maybe I could have been an athlete.’
During the same period, O'Connor also completed the London Marathon in 3:50:10.
The actor became so invested in training that he started finding ways to stay active even between takes.
‘Particularly during the main tennis match, Mike [Faist] and I would be doing laps of the tennis court or doing push-ups or burpees and just properly sweating,’ he said.
‘Put two actors on basically what is a stage, where there’s sweating and feeling boisterous, you’re going to have a bit of swagger. That really helped. It’s not a space I’m necessarily natural with, but I loved it. It felt good.’
Why O'Connor Had to Lose the Muscle Again
Unfortunately, the transformation didn't last.
‘I loved it. I had the time of my life and didn’t keep it up,’ O'Connor later admitted during Variety's Actors on Actors series with Daniel Craig.
Part of the reason was professional necessity.
After Challengers, O'Connor returned to complete filming on La chimera, in which he plays a man recently released from prison and struggling with the death of his girlfriend. Carrying the athletic physique he'd built for a professional tennis player no longer made sense for the character.
As a result, he had to shed much of the muscle he'd gained and become significantly leaner. According to O'Connor, that involved eating little more than a tin of tuna and an apple as his main meal each day.
Training Like a Boxer for Wake Up Dead Man
O'Connor's physical transformations haven't stopped there.
For Wake Up Dead Man: A Knives Out Mystery, he once again found himself back in the gym, this time developing the movement patterns and physique of a boxer.
‘Because I was working with Daniel Craig, he had a personal trainer on tap,’ O'Connor said. ‘Every morning I would go to the gym and train with Daniel.
‘When you're looking at a character, there is the question of the physicality of that character and what that means. This is someone who's got a background in boxing, so we did a bit of that.’
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_
