When actors become stars, they can choose one of three paths: play a number of roles that will basically repeat the original success; work in projects that are high-paying but undemanding; or take on bigger challenges, dig deeper into themselves and become better actors.

Luckily for audiences, Jake Gyllenhaal took route No. 3. In the past year, he shone as the TV host in Bong Joon-ho’s “Okja,” conquered Broadway in Stephen Sondheim’s “Sunday in the Park With George” and capped it all with a career-best performance in “Stronger.”

The actor plays Jeff Bauman, who lost his legs in the 2013 Boston Marathon bombings; after that, Bauman struggled physically and emotionally, while dealing with a public that made him an instant hero.

It sounds like a seen-it-before movie, but the film (written by John Pollono and directed by David Gordon Green) is much smarter and full of surprises. Gyllenhaal is raw and honest in a performance that Variety reviewer Andrew Barker called “superb.”

Gyllenhaal has been working for decades, in films that include “Donnie Darko” (2001), “Brokeback Mountain” (with an Oscar nomination), “Zodiac,” “Jarhead,” “Prisoners” and two other recent knockouts, “Nightcrawler” and “Nocturnal Animals.”

How does he pick material?

“I think about the script and the director, of course, but I also think about the department heads. Those talents really know what’s going on and so I trust them. They’ve proven to be a pretty good barometer of what’s going to be good.”

But when asked specifics about his work in “Stronger,” he instead talks about Bauman.

“I am more cynic than anything else, but he’s taken that out of me. I spent a year in his world; I needed to get it right. But deep down, I was struggling with doubt the whole time. There was no way I could live up to his story or the person that he is. Finally I realized Jeff himself was filled with doubt. He felt he wasn’t up to [the expectations of others and of himself]. And I think that realization was a bit of a fuel for the performance.”

The film addresses the fact that it’s a double-edged sword to be treated as a hero.

“Our culture has a real need, almost a painful need, for heroes. Our intention is to lift someone up, but we’re also putting a responsibility on the person, even when our intentions are good; we don’t realize what a weight it puts on them.”

He says Bauman grew into the greatness that was thrust upon him. “That’s the most incredible part, to have seen Jeff grow. He’s been 15 months sober and he’s so devoted to his daughter. To see the joy he brings people — I don’t know anyone who brings people the joy that he brings. He changed my life.”

Strength is generally seen as being stoic and rock-hard during adversity. But Gyllenhaal points out that true strength is also about vulnerability, caring and admitting loss.

As he saw changes in Bauman, he also felt a change. “I care a lot. But admitting that you care makes you more vulnerable. As I said, I tend to be a cynic, but I’m making myself a lot less ‘cool’ and allowing myself to be more vulnerable.”

By being less “cool,” Gyllenhaal is actually cooler. And by being more vulnerable, he’s become stronger. As the movie reminds us, life is full of surprises.