Zac Efron wasn’t the obvious choice to play the lead in the new film based on the Nicholas Sparks bestseller, abortion The Lucky One.

The actor isn’t well-known for his dramatic performances, check and the main character was written to be a few years older than Efron. But the actor fought for the role and eventually received it.

I recently spoke to producer Denise Di Novi about the film, ask why she loves adapting Sparks’ books and how Efron “really transformed himself” for the role of a Marine returning to the United States.

Di Novi has helped create some great Hollywood success stories ranging from 1990s Edward Scissorhands to 1993’s The Nightmare before Christmas to last year’s Crazy, Stupid, Love.

The Lucky One marks her fourth adaptation of a Sparks book. This one focuses on Logan (Efron), a veteran returning from Iraq who searches for a mysterious woman whose photograph—he believes—saved his life.

Efron, the young celebrity who rose to fame with movies like High School Musical and its two massively-successful sequels, worked tirelessly to prepare for the film according to Di Novi. He gained twenty pounds of muscle and visited Camp Pendleton to talk to some real-life veterans before the production.

But even before that, Efron had to argue why he could take on the role. The 17 Again actor seemed too young to play the battle-tested veteran. But Di Novi said that Efron argued that many real-life veterans are actually his own age. and that some of the friends he grew up were serving overseas.

That insistence helped earn him the part. And his positive personality didn’t hurt.

“Logan has to radiate a goodness, and that’s what I picked up on with Zac,” she says.

When I asked Di Novi about what appealed to her about the project, she said that “[t]he main thing is that it was a Nicholas Sparks book. It’s my fourth one and I love his books… [and] adapting them into movies.” She also told me that she appreciates the themes that he explores in his work – “love and redemption and faith and family.”

Di Novi, who considers Sparks’ The Notebook one of her favorite novels, said Sparks knows how to make appealing characters, the kind that resonate with audiences.

“People feel like it’s them in the books,” she said, adding that he “really understands women.”

In The Lucky One, though, Sparks had to understand veterans as well and their experiences fighting overseas. But Di Novi said that Sparks has a lot of friends and colleagues in the military and added that “I think he feels good about telling their story and showing what they’ve been through.”

In the film, Logan suffers from post-traumatic stress disorder when he returns to the United States. “I don’t think anyone comes back from combat unscathed,” the producer said. But unlike other movies, this one never denigrates his character or the military itself.

“[Logan] is a good person and has a lot of integrity, and that’s one of the things I love about the character,” she says. “That integrity isn’t something that we see presented at the theater very often, so it’s something to be appreciated in films like this.”

The Lucky One is in theaters now.