Colin Donnell on Stripping Down for Broadway's “The Shark Is Broken”: 'The Gym Was My Friend'“ ”(Exclusive)

The 'Chicago Med' alum opens up to PEOPLE about his skin-showing scene in the 'Jaws'-themed play

Colin Donnell never thought he'd be appearing on Broadway in just a Speedo.

The Chicago Med alum and theater veteran is currently treading the boards again in The Shark Is Broken, a comedic play that theatricalizes the behind-the-scenes shenanigans that took place when the cameras stopped rolling between takes of Steven Spielberg's 1975 classic blockbuster, Jaws. But when he first read the script before auditioning to play the late Roy Schneider — one of the three Jaws stars, along with Richard Dreyfuss and Robert Shaw, who are the focus of the show — he was surprised to learn that he just might have to show a bit more of himself.

"I certainly didn't think that my first play would would require this," he recalls to PEOPLE. "But there's a scene where Roy strips down into his Speedo and starts sunbathing while filming is delayed, And when I saw that had been added, I was like, 'Oh... maybe it's time to really dial it in at the gym.' "

Dial it in Donnell did. Fans following the Arrow star on Instagram saw the transformation play out in real time, in a series of workout videos he's been sharing. "I'd been focusing on getting into shape for awhile, but nothing really motivates you more than being exposed to an audience like that," he jokes. "I definitely put things into high gear after that."

Related: Colin Donnell Shares Photo of His Impressive '#DadBod,' Says He's in 'The Best Shape of My Life at 40'

High gear meant ramping up his exercise routine. "I didn't go the Ozempic route, but that sure would have been a little bit easier," he laughs. "But no, the gym was my friend. I worked out a lot. And I love working out so I just tried to have fun with it — hiking, walking, swinging kettlebells around, things like that."

Changing his diet was also crucial to his success. "There's that old saying that abs are made in the kitchen and it's such a shame that they're right," he says. "It really all came down to diet. I don't have a secret sauce to it; I used an app called Macro Factor, which helped me track my nutrition. And then I just stayed focused on it and really built a routine. This is the first time I've been back doing a theater production since having kids, and I'm living an hour outside the city now, so in order to do this while still doing all the things I needed to do every day, I had to build a schedule and really stick to it. And it turns out, I really like having a schedule."

"Thankfully, my wife [Patti Murin] was so supportive of me; I'd be totally remiss if I didn't shout her out from the rooftops," he adds. "The fact that she was able to hold it down and give me the space to do what I needed to do and focus on the work was just incredible. So I have to give credit where credit is due because her help was everything."

It also helped that Donnell's body was able to fit an aesthetic that matched Schneider's at the time he made Jaws. "Men in the 1970s, they tended to be more svelte," he says. "Roy certainly was a long, tall, thin glass of water. And while I'm not a naturally skinny guy, when my body started to transform and suddenly I had abs, I was like, 'Oh... I like this! This works for me!' "

Changing his body wasn't the only way Donnell transformed into Schneider for the play, although researching Jaws, surprisingly, wasn't one of them. "It's not about playing Roy — or even Richard or Ian — in Jaws," Donnell says. "We're actors playing actors who were playing characters in a movie. So we're trying to play the people, not the parts."

To do that, Donnell rewatched Jaws, sure, but primarily focused on old interviews with Schneider that were shared on YouTube.

"Thankfully, Roy was so famous back in the day that there's just a wealth of information to pull from," he tells PEOPLE. "There was one interview in particular, it wasn't form the 1970s but it was from an appearance Roy did on The Graham Norton Show in the 1990s. And I just kept going back to it time and time again and studying his mannerisms. There was a certain way he sat and tended to sit in all interviews. He was this very upright-postured, cross-legged man who was in total control of his body. He talked a certain way, laughed a certain way, gestured a certain way. It just perfectly encapsulated who I felt he was."

Related: Richard Dreyfuss Visits Broadway's Jaws-Themed Play The Shark Is Broken, 48 Years After Starring in Film

"I mean, he was such a self-assured person," Donnell continues. "Even that Speedo scene, that was him. He had no problems ripping off his clothes and sitting out on the deck, soaking out the sun. There's a director friend of mine who sent me a picture of Roy's beach house somewhere on Long Island, and he told me this story. He was like, 'I never walked by that house without seeing Roy either dressed in all-black or totally shirtless, standing at the balcony, staring out at the sea with a cigarette dangling from his mouth soaking it all in.' And I was like, "That's perfect. That's who this guy is.' Roy was always just watching and observing and doing his thing."

The Shark Is Broken began performances at the John Golden Theatre in New York City on July 25 ahead of an Aug. 10 opening. Prior to Broadway, the comedy — which is directed by Guy Masterson — played critically acclaimed runs at the Edinburgh Festival Fringe and on London’s West End.

Tony nominee Alex Brightman, who portrays Dreyfuss, stars alongside Donnell in the play. Ian Shaw, who is making his Broadway debut with the project and plays his father in the show, penned the play alongside Joseph Nixon. The actor-playwright, now 53, was just 8 years old when his father died at the age of 51 in 1978, but created the play with the help of his dad's diary, which chronicled the English actor's lifelong struggle with alcoholism and tormented attempts to stop drinking.

Related: Son of 'Jaws' Star Robert Shaw on 'Release' of Playing His Dad in 'The Shark Is Broken' (Exclusive)

The action takes place on the set of The Orca, the fictional boat where the three actors wait for Jaws' famous mechanical sharks to be repaired so they can shoot. And while loyal fans will walk away with a deeper understanding of their treasured movie, there's plenty for those who may not be as familiar with the film.

"We get people at the stage door who have seen the movie hundreds of times and those who don’t know it as well. And the thing about this play is it offers all the behind-the-scenes mishegoss that went into making this movie that has miraculously lived on for nearly 50 years, so it works on all levels," Donnell says.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

"I'm going to miss it," he adds of doing the play. "From the moment I read it, I was really struck by how funny and surprisingly moving it was. Ian has crated this lovely tribute to his father and it makes the piece more about what it appears on the surface. And doing it with Alex and Ian has been a dream. I've obviously done a lot of musicals, but I couldn't ask for a better experience for my first place."

"Maybe the next one, I'll keep more clothes on."

The Shark Is Broken is now playing through Sunday. Click here for tickets.

For more People news, make sure to sign up for our newsletter!

Read the original article on People.