Jake Gyllenhaal Talks 'The Covenant' and His Viral 'Road House' Transformation (Exclusive)

Yes, the actor knows about your 'Jacked Gyllenhaal' memes.

Yes, Jake Gyllenhaal knows all about those "Jacked Gyllenhaal" memes. 

The actor -- who is currently in intense UFC training for the upcoming Road House remake -- recently sat down with ET's Cassie DiLaura to discuss his new film, Guy Ritchie's The Covenant, and weigh in on the internet's unquenchable thirst for his movie muscles.

"That's a wonderful nickname," he joked. "It's been an incredible experience and it is [amazing] working with actual real fighters, working with the UFC, reimagining a classic. There's been a lot of the physical [work]."

That's not to say that filming The Covenant was a walk in the park. The Guy Ritchie-directed film drops the actor into the middle of the United States' War in Afghanistan. Gyllenhaal plays U.S. Army Sergeant John Kinley, who is saved from the Taliban by his local interpreter, Ahmed (Dar Salim), and has to repay the favor when Ahmed is endangered by his actions.

"I think it's a movie about doing good reluctantly," Gyllenhaal said of The Covenant, which was also written by Ritchie, along with Ivan Atkinson and Marn Davies. "It's not full of sentimentality. It's two guys who are sort of in an arranged marriage, because at the beginning of the movie, my character loses his interpreter and then they're assigned to each other. They don't really like each other very much."

"I think it's a movie about America and the best that we can be," he continued. "I think we are a country of heroes, and oftentimes reluctant ones, but that's our fabric. And I hadn't read something in a long time... that made me proud to be an American. And this movie does. So that's really what drew me to it."

For Salim's part, he teasingly shared that he only signed on to the film to work with "arguably one of our generation's best actors."

"It was a huge bonus that the story is so strong," he added honestly. "They're thrown in a situation where they have to trust each other. And they end up, in this very unsentimental way, doing the right thing, and it just shows that even though it's not like it's not a true story, but it's based on the truth that all interpreters did put their lives at stake every day. All U.S. soldiers did put their lives at stake, trying to do the right thing. And at the end of the day, they end up saving each other's lives and doing the right thing and showing that so much more, you know, unites us as human beings then we're all the time told what divide us."

Both actors shared that they've played multiple military roles in the past, so they weren't intimidated by the physicality the film demanded. However, what was a bit jarring was Ritchie's style of changing things up on the fly, altering lines, moments and even whole scenes from take to take.

"Coming on set the first week was very scary," Salim admitted. "You're like, with Jake Gyllenhaal and Guy Ritchie and you've come prepared, and you want to show them how good you are. And then you got to start from scratch. But that was then the strength of the relationship."

"He's a very fluid filmmaker. You discover things on the day and then he adds them to the story," Gyllenhaal agreed. "And he's writing as he goes. I mean, everything is written by him, but it is changing based on our relationship, discussions we've had, and then the movie evolves. I can tell you 10, 15 times lines were said that he then brought back -- things that were improv, something he throws at you off screen, he goes, "Say this line, Jakey!" And then the movie gets made like that. It's pretty interesting."

Guy Ritchie's The Covenant is in theaters April 21.