How Kingsley Ben-Adir Prepped for Bob Marley: One Love — Guitar in Hand — on the Barbie Set (Exclusive)

Kingsley Ben-Adir found his groove as Bob Marley while making Barbie.

In the new issue of PEOPLE, the actor, 37, recalls how he learned to play the guitar and studied the musician’s Jamaican accent and Patois language for the Bob Marley: One Love biopic while he was playing one of the Kens in Greta Gerwig’s blockbuster movie.

“I knew I was going to be on Barbie for just under four months or three and a half months, and I needed to get going [on preparing [for One Love]. There was so much to learn and do, and I spoke to Greta about it,” says the U.K native.

“I really felt like I needed to get going, especially with the guitar and the learning of the language, it's a lot of foundational things that you need to get set first before you can really move on,” he continues.

Ben-Adir says he used his breaks wisely to make it work.

“On set, there's a lot of downtime. There's a lot of between setups and stuff, so it just made sense to come into Barbie every morning with a guitar and a laptop,” he says. “When there was a few hours, I just sat up behind the Mojo Dojo Casa and just practiced some Patois and some chords, and then came back for ‘I'm Just Ken.’”

“Everyone was really nice. I think everyone on Barbie understood. The [assistant directors] and staff, they understood that there was a lot of pressure and they were really helpful,” he says. “They'd always wrap me as early as they could, like, ‘You've got half an hour, go learn 'Redemption Song' and come back.’”

Ben-Adir did not, however, serenade director Gerwig or star Margot Robbie. “They were far too busy making the biggest movie of the last 10 years,” he quips.

The actor, who has portrayed real people like Barack Obama in The Comey Rule and Malcolm X in One Night in Miami says taking on the role of Marley was different because he’s an artist.

“I've played real life people, but I've never played an artist, but that was what was interesting about it as well,” he says. “It felt a bit dangerous because I was like, I'm going to be starting from scratch.”

Ben-Adir says the toughest part was trying to learn everything — singing, guitar, language, accent — all at once.

“The singing and the learning of the guitar was challenging for sure, but they were all good challenges. They were all fun challenges,” he says. “It wasn't one thing in particular. It was the many different things altogether at the same time, starting from scratch.”

Bob Marley: One Love is in theaters nationwide Feb. 14.

The special issue of LIFE: Bob Marley is available now.

For more on Kingsley Ben-Adir, pick up the new issue of PEOPLE.