Matt Damon is back as Jason Bourne in... Jason Bourne

File photo of Matt Damon in Los Angeles. on 10/08/15. See PA Feature FILM Damon. Picture credit should read: Paul A. Hebert/Invision/AP/PA Photos. WARNING: This picture must only be used to accompany PA Feature FILM Damon. UK REGIONAL PAPERS AND MAGAZINES, PLEASE REMOVE FROM ALL COMPUTERS AND ARCHIVES BY 08/08/16

Matt Damon is back on the big screen in summer's most anticipated blockbuster, Jason Bourne. He talks to Kate Whiting about getting back in shape, world politics and why baring his pecs was a '˜big deal'

Matt Damon is describing what it’s like to film a fight scene - and can’t help but chuckle at his day job.

“It’s just utterly ridiculous, we’re grown men play-fighting, you know what I mean? That’s what my job is!”

And there’s a lot of ‘play-fighting’ in his latest movie, the long-awaited action sequel Jason Bourne. The actor is back, literally by popular demand, playing the amnesiac assassin, 14 years after the franchise began with The Bourne Identity back in 2002.

Undated Film Still Handout from Jason Bourne. Pictured: Matt Damon as Jason Bourne. See PA Feature FILM Damon. Picture credit should read: PA Photo/Universal. WARNING: This picture must only be used to accompany PA Feature FILM Damon.

“People wanted to see it,” he says. “Every airport I’m in, or every time I’m walking down the street and somebody stops me, that’s the first question, ‘Are you going to do another Bourne movie?’ So it’s exciting on one hand, but there’s also a lot of pressure.

“We definitely left it all on the field,” adds Damon, of the sheer effort that went into making it. “I hope it’s the movie people wanna see. I’m at peace with where we are.”

When we last saw Bourne, in 2007’s The Bourne Ultimatum, he had exposed the CIA’s controversial Blackbriar programme, and was swimming off into obscurity.

At the start of Jason Bourne, we discover just what he’s been doing with his time since: bare knuckle fighting on the Greek/Macedonian border.

“He did liberate himself from this Jason Bourne identity, but that hasn’t brought him any peace. He’s an incredibly tortured soul and you find him in a very dark place at the beginning of the movie,” notes Damon, who has four children with wife of 11 years Luciana Bozan Barroso (three daughters together and a step-daughter from Barrosa’s previous marriage).

To look the part, the actor, who turned 45 last October, went on a “really boring” diet of protein and vegetables - “that was the hardest part, I like to eat!” - and spent hours spent working out in the gym.

“Just getting into shape was an up-at-dawn siege every day,” he admits, adding that director Paul Greengrass told him it would only work if he looked like he’d “suffered” (“Those are the words I repeated to myself thousands of times in the gym...”).