EXCLUSIVE: How 'Saving Private Ryan' Helped Prepare Vin Diesel for 'Billy Lynn's Long Halftime Walk'

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Billy Lynn's Long Halftime Walk brings to life a harrowing story from the Iraq War, which meant a grueling, two-week boot camp for the cast -- all except for one.

"I did my boot camp in Saving Private Ryan," Vin Diesel told ET's Nischelle Turner during a recent sit-down. "It was a scheduling thing really, but luckily, I did a very intense boot camp for Saving Private Ryan. I did a self-imposed boot camp. I went away for a week. I bought equipment, and trained on a beach and got ready to be a soldier."

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From three-time Academy Award-winning director Ang Lee, Billy Lynn's Long Halftime Walk tells the story of 19-year-old private Billy Lynn (Joe Alwyn), who becomes a hero after an agonizing battle in Iraq and is brought home temporarily for a victory tour. Through flashbacks, viewers learn what really happened to Lynn and his Bravo Squad, contrasting the realities of the war with America's perceptions.

"I wanted to work with Ang Lee for a while," Diesel told ET. "When I got the call from him, he said, 'This is a soldier who is a cross between Rambo and Buddha.' And he said, 'Vin, this character is really my touch, because I've embellished on this character beyond the book, and you're my spirit animal.'"

In addition to Diesel and newcomer Alwyn, the film also stars Steve Martin, Chris Tucker, Kristen Stewart and Garrett Hedlund. Stewart gushed over Alwyn's performance while talking to ET, giving him high praise for his dynamic big-screen debut.

"I know that he's never done it before, but he brings something to this that just exemplifies something super modern," she said. "There's something nice and base and traditional and good about him, and you can't fake that."

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Stewart and Alwyn's characters are romantically involved in the movie, which called for some intimate scenes that Alwyn joked were "intimidating."

"I'm still not able to [look at her]," he joked.

While Tucker is no newbie to showbiz, his casting is different from any other role the comedian has taken on in the past. He says he resonated with the part because of all the soldiers he's met in airports across the country.

WATCH: 'Billy Lynn's Long Halftime Walk' Trailer

"I met one guy with a prosthetic leg, and I offered him my first-class seat and he said, 'No, I know you're tired and you're getting ready to go do a show,'" Tucker recalled. "I thought that was great ... that made me want to do this movie."

Billy Lynn's Long Halftime Walk, based on Ben Fountain's bestselling novel, opens Nov. 11.