“A couple of days ago I said, I’m getting off the hamster wheel. I really did.”

Bradley Cooper has tucked his six-foot-one-inch frame between the plump pillows of a sofa at Philadelphia’s Rittenhouse Hotel, 25 minutes from his hometown of Abington, Pa.

He’s in this cushy but familiar spot to discuss “Limitless,” the film that has finally elevated him to the role of marquee movie star and cast him opposite his idol, Robert De Niro. Yet, here he sits, revealing to a reporter that just last week, he considered quitting acting.

“Look, I’m very blessed, very lucky that I work . . . but that doesn’t mean this job’s easy,” Cooper continues, noting that getting passed over for a coveted part — he won’t say which — prompted the flicker of career angst. “I don’t find it easy. I find it very difficult. I find it hard to be an actor, because you have to deal with so much rejection.”

It’s hard to believe a guy like Bradley Cooper ever wrestles with self-doubt. For starters, just look at him. He exudes an effortless, golden-boy handsomeness, with eyes so crystalline Crayola should strongly consider naming a crayon after them.

And look at his career. After years of playing supporting roles in TV shows like “Alias” and movies like “Wedding Crashers,” Cooper’s moment appears to have arrived. Following the monumental box-office success of 2009’s “The Hangover” — in which he managed to be charming while simultaneously driving a cop car on a Las Vegas sidewalk and complimenting a woman’s cleavage — more Hollywood doors have started to swing open, including the doors that led to the lead in “Limitless.” The psychological thriller, which opens Friday, also gives Cooper, 36, his first executive producer credit.

In the film, Cooper has to carry virtually every scene as a struggling writer who takes a black-market drug that maximizes his brain power and quickly turns him into a wealthy, well-connected investment genius. Suffice it to say, that success comes with a price. And for Cooper, the role comes with an irony he seems keenly aware of: It took the Georgetown University graduate almost a decade to finally star as an overnight success.

“The bottom line is, if this movie doesn’t do well, it’s going to be very hard to get an opportunity to play another role like this,” he says.

Cooper, who describes himself as an optimist in life who always prepares for the worst in his career, may be cautiously hopeful. But others are confident.

“He’s going to continue to rise. He’s an amazing actor,” says James Lipton, dean emeritus of the Actors Studio Drama School at Pace University, where Cooper earned his MFA. Lipton also happens to be host of Bravo’s “Inside the Actors Studio,” which will feature Cooper in an emotional appearance Monday — the alumnus gets verklempt several times within the first 15 minutes alone — that marks the first time a graduate has become a guest on the show.

 “He has already risen to the top fraction of a percent of American actors, and I don’t think there’s any way, short of turning into Charlie Sheen and self-destructing, that he will not continue to progress,” Lipton says.

Cooper seems determined not to self-destruct and to keep certain elements of his life private, particularly his reported relationship with actress Renee Zellweger. Neither Cooper nor Zellweger has ever officially confirmed the long-term romance to the press, although her presence in the audience during that “Inside the Actors Studio” episode, not to mention numerous photos and online videos of the two, suggests their partnership is real.

“Yeah, I just don’t talk about that stuff,” Cooper says politely but firmly.

Given what he’s gone through to get where he is — Cooper notes that not so long ago, bouncers wouldn’t even let him into L.A.’s SkyBar — he also knows better than to take too seriously the paparazzi attention, his inclusion on People’s sexiest-man-alive list or even the hordes of wonky fans that mobbed him at last year’s White House Correspondents Dinner.

“If ‘The Hangover’ had happened to me at 23, I think I’d be really screwed,” he says. “Because notoriety — if you don’t know what it is and how it has nothing to do with you and it’s gone in an instant and it means nothing that’s of any worth — it has the facade of answering all those problems. You know, of giving you all those things. So if you let it do that, you’re really in trouble. But for me, I don’t even have to try to not let it get in. Because it’s so clear to me what it is.”

That attitude comes as no surprise to Brian Klugman, an actor, screenwriter and close friend of Cooper’s since the fifth grade. Klugman, who plans to co-direct Cooper and Jeremy Irons in “The Words,” a drama he also co-wrote, says the guy who blared his stereo and obsessed over “Apocalypse Now” in high school hasn’t changed. He’s still “the same nerd” he knew back at Pennsylvania’s Germantown Academy.

“On some level,” Klugman says, “I feel as if he has been built to handle this. He’s just really grounded.”

Cooper is coming off of a particularly hectic few months that included filming “The Hangover 2” in Bangkok (it comes out Memorial Day weekend), doing reshoots for “Limitless” and mourning the loss of his father, Charlie, who died in January after a long illness. (The first thing he says about that “Actors Studio” episode, which was taped back in October: “My dad got to see it.”) More than anything, the actor who once waited tables at D.C.’s Cafe Milano, is just trying to live in the moment and relish the rewards and esteemed company he’s earned after years of paying dues.

“We were doing some press yesterday, and they asked [me and De Niro] who our idols were,” Cooper says. “I was talking about him, and Albert Finney and Daniel Day-Lewis and Tom Courtenay. And [De Niro] starts talking about Walter Huston and Marlon Brando, Montgomery Clift. And I was just looking at this guy next to me, my buddy. And I thought, what the hell is happening? What is happening?”

Cooper smiles widely. It’s pretty clear from his amazed, elated look that he’s not jumping off the hamster wheel anytime soon.