The "Black Adam" movie has been years in the making, but for star Dwayne Johnson, it was all worth waiting for.

The actor, who plays the titular DC anti-hero, told "Good Morning America" the film is "a representation of trying to be resilient, pushing this thing and really fighting for this thing." Talk of Johnson portraying the character first surfaced 15 years ago, in 2007, and he eventually confirmed he would be playing the character back in 2014.

When getting into character, which he said is "certainly a departure" from anything he's done before, Johnson said he recalled times in his past where he felt "really constrained" and had people telling him what he could and could not do.

For example, Johnson said he thought back to his start in Hollywood "many moons ago" -- fans first saw him on the big screen in 2001's "The Mummy Returns" -- when he was told that, as someone from the pro wrestling world, he'd have to make changes if he wanted to be like the biggest movie stars at the time, George Clooney, Johnny Depp and Will Smith.

Johnson said he was told he shouldn't call himself The Rock -- his ring name -- and that he'd have to go on a diet and not go to the gym in an effort to lose weight because he was "too big."

"If you don't know any better, you buy into it," he remembered. "And I bought into it for a couple of years before I said, 'This ends right now, and I'm going to be myself and at least if I fail, I'll fail being me.' "

Johnson said tapping into those memories helped him relate to his latest character because "a lot of that, those elements, are what surrounds Black Adam's life and his existence," being told what to do and how a superhero should act.

"Black Adam says, 'Well, I'm going to do it Black Adam's way,' " he said.

Johnson said "Black Adam" means a lot to him, calling it "the movie of my career, the most important movie I've ever done -- arguably will ever do."

Though he said kids usually keep your ego in check, Johnson said his daughters are excited to see him play Black Adam and he's even going to show it to them -- at least "certain parts."

Still, Johnson, who is dad to daughters Simone, 21, Jasmine, 6, and Tiana, 4, said that while he loves being in films, the role of father is "my existence."

"I will tell you, that's my favorite role," he said.

"Black Adam" opens in U.S. theaters on Oct. 21.