"I was just at the right time in my life to bring that kind of focus and dedication to it," Cooper said
Credit: Gregory Pace/BEI

While Bradley Cooper was able to bulk up for his turn in director Clint Eastwood’s American Sniper, his real challenge was taking on the intensity and emotion of his character.

In the film – which has now scored six Oscar nominations including Best Picture and Best Actor, for Cooper – the star plays Chris Kyle, widely regarded as the deadliest sniper in American history. The Navy SEAL served four tours in Iraq before returning home, but the battle didn’t end when he was honorably discharged.

Kyle struggled with post-traumatic stress disorder when he returned from the frontlines, yet was able to overcome it and help other vets – before he was allegedly killed last year.

“It was just an honor,” Cooper, speaking to reporters at the New York City premiere of the film on Dec. 15, said of playing Kyle. He called the role “the benefit of being an actor.”

Believing he “was just at the right time in my life to bring that kind of focus and dedication” to the part, Cooper added that he learned a lot from playing the intense, standoffish Texan and decorated war vet.

“There’s something about how stoic he was, and it was all sort of in his eyes as a human being, how gentle he was, how complicated he was, and it was really sort of a practice in almost doing nothing and just sort of trusting that whatever’s going inside is going to read,” Cooper – who scored his third consecutive Oscar acting nod with his performance in American Sniper – said.

One person impressed with the actor’s performance: director Eastwood. “He’s a wonderfully talented guy and the perfect guy to play the part,” Eastwood told reporters. “He’s dedicated I never catch him acting in this film, which is a compliment.”

Cooper said he felt pressure to perform in the film. “It was the responsibility I had to his family to preserve his legacy that weighed on me,” he said in reference to Kyle’s widow Taya and two children.

While, surprisingly, Cooper was snubbed for Golden Globe and SAG nominations, Taya was happy with the end product. After seeing he film for the first time, “I felt a sense of contentment that they did it right,” she tells PEOPLE.

Recalls screenwriter Jason Hall of that same screening: “Taya came out of the movie crying. She gave me a big hug and said, ‘I just spent two hours with my husband. You all brought my husband back to life.’ It was a really good feeling.”