It's very good to be Bradley Cooper these days

NEW YORK - On a recent Saturday afternoon, Bradley Cooper took his curtain call at Broadway's Booth Theater, where he's starring in "The Elephant Man." He then had to race to a meeting, give an interview for this article, and find time to eat and nap before taking the stage again for his 8 p.m. show.

There's definitely a lot going on for Cooper, who turned 40 earlier this month. Along with eight Broadway performances a week, he's been busy promoting one of his biggest movies to date, as both actor and producer: Clint Eastwood's "American Sniper," in which Cooper transforms himself - to much critical acclaim - into late Navy SEAL marksman Chris Kyle. And on Thursday, he earned his third career Oscar nomination for the role, edging his way into a very crowded best-actor race.

There's even a report (way premature, the actor says) that he plans to make his feature directorial debut soon. Is it an exaggeration to say that all in all, this is a huge career moment for Cooper?

In an interview conducted before the Oscar nominations came out, he responded modestly: "I think the fact that I had a chance to play Chris Kyle and Joseph Merrick (subject of 'The Elephant Man') in the same year is huge for me," he said. "Absolutely."

It's certainly a season for cinematic portrayals of real-life characters: Martin Luther King Jr in "Selma" and physicist Stephen Hawking in "The Theory of Everything," to name just a few. Cooper hadn't portrayed a real person before, and says the responsibility he felt in playing Kyle, who died in 2013 with the legacy of being the most lethal sniper in U.S. military history, was "massive."

"There's a family that's still alive and children that are still alive," Cooper says. "So this film, if we get it right, it will matter to them forever. For the rest of their lives and their children's lives, potentially. So that was a huge responsibility." (There was also the comment Kyle's father reportedly made to Eastwood: "Disrespect my son and I'll unleash hell on you.")

Cooper's response to the challenge, he says, was "to put a tremendous amount of pressure on myself." For starters, that meant "gain 40 pounds and literally learn exactly how he spoke."

He tries to describe the days spent prepping for the film: "Wake up 5 a.m., put on my headphones right away, listen to his voice right away, just to get it in my system," he recounts. "Ride my motorcycle to the gym, where I have big blowup photos of him."

Two and a half hours of heavy lifting would follow, staring at those photos and listening to Kyle's playlist, given to him by the sniper's widow, Taya. Then two hours at home with a dialectician. Back to the gym for two more hours, then back home for more dialect work, until 8 p.m. "I would do that five days a week," he says. "Yeah, it was intense."

Cooper also spent hours listening to every interview Kyle had ever done. Unfortunately, he had no personal memories to go on, only a brief phone conversation. Kyle was shot and killed at a shooting range in February 2013, by a former Marine he was trying to help.

And so the research was extensive. "What we really cared about was first of all the family believing that it was Chris up there," Cooper says. "They were very, very positive in that direction. And that meant the world to me."

Taya Kyle is quick to confirm her approval. "I really don't know how he did it as well as he did," she says. "So many of Chris' friends said it's almost eerie watching it. I'm eternally grateful. He got the mannerisms and the way he moved and breathed, all those things."

The actor's recent success doesn't surprise the dean of his former acting school; That would be James Lipton, host of Bravo's "Inside the Actors Studio," who auditioned Cooper when he was a student at Georgetown.

"The scene he did wasn't great, but I had a very strong feeling about him," Lipton says. By the time "Coop," as he's called, did his master's thesis - scenes from "The Elephant Man," as it happens - Lipton says he thought: "He's going to be a very important actor."

Cooper's Broadway run ends Feb. 22, and he hopes to bring the show to London this summer. As for film, whatever's next, he doesn't think it'll be easy to top "American Sniper."

"I was just saying to my buddy this morning - 'if we're lucky, we'll get to do this again,"' he says. "But it'll never get better than this."