Earlier this week, during an appearance on The Late Show, Krasinski opened up about how he got ripped for his role as a CIA contractor in the upcoming movie 13 Hours: The Secret Soldiers of Benghazi (in theaters Jan. 25). He even joked to host Stephen Colbert that his wife, Emily Blunt, "hates" his new buff body. "She would way prefer to have doughy guy back," he quipped.
Krasinski was kidding, but some viewers assumed he was serious. "I can't believe people took that the wrong way. I was totally kidding," the actor, 36, told NBC Thursday. "She is a huge fan of that, but of course, people will write what they want to write. But no, she's a big fan of it."
To prepare for the part, he worked with trainer Jason Walsh, who also whipped Bradley Cooper into shape for his role in 2014's American Sniper. "I actually introduced Bradley to Jason Walsh. He's the greatest guy. I actually worked out with Jason a little bit for this movie Aloha that Bradley did," Krasinski said during the press junket. "I was there when Bradley was training for American Sniper, which I think gave me this wrong idea. I was like, 'Oh, I've gotta get that big.' So, I gained a lot over the holidays before training, and that wasn't what my trainer wanted."
Krasinski's goal wasn't to look like Arnold Schwarzenegger during his bodybuilder days. Most CIA contractors are muscular yet agile, he explained, "so it's not about looking like giant weight lifters. It's actually about how quickly can you move, how strong you can be, and that's really fascinating." He's kept the workouts up, too. "After a little while, you get a little addicted to it."
Like Blunt, Krasinski is proud of his muscular frame. "I think, for me, getting in the best shape of your life at age 35 is weird," he said, "because I think you imagine being in the best shape of your life at 18 or something like that," he told NBC. "So, now that I'm here, I can't give up on it."
Krasinski cited a peer who went through a total body transformation several years ago and has remained in excellent shape ever since. "I remember Chris Pratt, it was really inspiring for him to say, 'I'm never going back,'" he said. "I went, 'You know what? I think I'm with you, Chris.'"
For more from Krasinski, tune in to E! News tonight at 7 and 11.
13 Hours: The Secret Soldiers of Benghazi is in theaters Jan. 25.