Chris Pratt enters a new Galaxy

Pratt says his buff physique is “essentially a costume that I worked really hard to put on.”

After Chris Pratt tweeted a shirtless photo of himself to flaunt the shape he had gotten into for Zero Dark Thirty, he received, he says, a “giant ball of criticism” from his friends. It also helped land him the lead in one of the summer’s biggest movies.

When Marvel executives Kevin Feige and Louis D’Esposito sat Pratt down to discuss starring in Guardians of the Galaxy, they pulled out the photo (it had gone viral) and asked: “How long would it take you to get into this shape?”

The photo had changed how both Pratt’s fans and Hollywood executives saw the actor best known as the lovably goofy Andy Dwyer on NBC’s Parks and Recreation. Pratt says his buff physique is “essentially a costume that I worked really hard to put on.”

“No one has head shots and resumes anymore. They just Google you,” he said in a recent interview. “If you Google me, it would be a fat, sweaty, albeit hilarious picture of me. It was not what I wanted people to be seeing if I was going to be in contention for these roles.”

In Guardians of the Galaxy, which Disney will release August 1, Pratt stars as a cocksure space adventurer who unwittingly becomes the target of an intergalactic manhunt. For Marvel, it’s a lesser-known comic-book property with a more comic, off-kilter story. (Bradley Cooper voices a digitally rendered raccoon.)

Following supporting turns in Moneyball and Her, it’s a significant bump into big-budget stardom for Pratt. He’s currently in Hawaii shooting another potential blockbuster, Jurassic World. It’s directed by Colin Trevorrow, who made Safety Not Guaranteed with Pratt’s TV wife, Aubrey Plaza.

“This is definitely uncharted territory for me,” says Pratt. “It does feel like I’m starting another chapter.”

Pratt also voiced the lead in the hit animated film The Lego Movie earlier this year. With a Guardians of the Galaxy, Pratt — often penniless on Parks — may surpass $1 billion at the box office in 2014.

“That’s pretty cool,” he says, contemplating the possibility. “Yeah, that will be a good year. I feel like I’ve just been invited along for the ride.”