Bruce Dern takes a bow at the Cannes Film Festival with a new documentary on his life

Dern had to play the long game. But for the actor, an avid marathon runner who used to jog from his Malibu home to set, acting has always been an endurance sport.

Dern, who turns 90 next month, came to the Cannes Film Festival this week to take a well-deserved bow.

“Dernsie: The Amazing Life of Bruce Dern,” a documentary about his long-distance career, premiered on Thursday at the festival.

“I see a journey, a long uninterrupted journey,” Dern said in an interview alongside his daughter, Laura. “A bunch of folks got together and said: ‘Bruce Dern could play.’ That’s all I wanted.”

Cannes, like most things for Dern, holds plenty of stories. He first came here, he says, with Alfred Hitchcock for “Marnie.” In 2013, he won best actor in Cannes for one of his few leading performances, in “Nebraska,” directed by Alexander Payne.

Along the way, Laura Dern has often been there. As a child, Hitchcock gave her a mini director’s chair to sit in. On “Nebraska,” Laura — who starred in Payne’s first feature, “Citizen Ruth” — for a week rode in the trailing van with Payne. She’s currently in the south of France to shoot the fourth season of “The White Lotus,” but she was eager to join for her dad’s moment in Cannes and help him down the red carpet.

“What I loved about witnessing dad’s career is when I was a little kid, people would come up to me and say, ‘Boy, do I love to hate your dad,’” she said. “That was a common quote, which meant they had fallen in love with this character even though he shot John Wayne or the various things he was up to.”

“Blew up the Super Bowl,” says her father, grinning.

A character actor villain

Dern has done some terrible things on screen. He’s hit Barbara Stanwyck (“The Big Valley”). He’s lynched Clint Eastwood (“Hang ’Em High”). He killed John Wayne (“The Cowboys”), an offense some never forgave him for.

In 1977’s “Black Sunday,” Dern played a disturbed Vietnam veteran pilot who tries to blow up the Super Bowl with a blimp full of explosives. Such exploits, and the live-wire intensity that Dern brought to them, made him idolized by filmmakers like Quentin Tarantino. In the documentary, he calls Dern “one of the finest and most entertaining examples of great American acting.”

That unpredictability also makes Dern a hold-onto-your-seat interview. He has stories to tell, and likes telling them. Tangents come like haymakers. That made for a particular challenge for “Dernsie” director Mike Mendez. He and Dern began just talking over breakfasts at IHOP. For the documentary, he tried to recreate that experience while vainly attempting to keep Dern on subject.

“I would try,” sighs Mendez. “But as anybody who’s ever spoken to him or interviewed him, he’s like a wild bull. You can feed him a question and his mind is just going to go wherever it’s going to go.”

Talking in Cannes, Dern’s free-flowing topics included Hitchcock’s treatment of Tippi Hedren, his friendship with Jack Nicholson (“He was ahead of us all”), what Stanwyck said to him after slapping him (“She said, ‘I’m not going to even ask you if I hurt you’”), a jogging route to Santa Barbara and a near word-for-word recital of the climactic scene of “Nebraska.”

Improvising the ‘Dernsies’

But a through line to “Dernsie” is its title’s meaning. Throughout his career, Dern was known for his off-the-cuff improvisations that jolted scenes into life. The term he credits to Nicholson, who liked a finger snap Dern added during the making of Nicholson’s 1971 film, “Drive, He Said.”

“He said, ‘I want to say something. That little snap of the fingers that he just did? He’s been doing that s--- for 10 years and no one ever gave him a chance to film that. That’s a Dernsie,” Dern says.

During a scene with Brad Pitt in “Once Upon a Time … in Hollywood,” Dern added a line — “You did something today that really touched me. You came to see me” — that he says came out of how he felt to be a part of the movie.

“And afterward Brad had tears in his eyes and picked me up like a little baby and carried me around the set,” says Dern, laughing.

“I don’t rehearse it,’ he explains. “Once the switch is on, you’re going. The Dernsies, I don’t know what they’re going to be. I take from everything that’s going on around, even if it has nothing to do with it.”

These aren’t just the reminiscences of a retired actor, either. Dern still very much has the mindset of a working actor. He plans to keep going until he drops. It’s an attitude that Laura’s mother, Diane Ladd, who died last year, also shared.

“We read so much about longevity,” she says. “Now the studies are showing that a purpose driven life, more than a Mediterranean diet, more than all the different things people debate, is in fact the greatest act of longevity. My parents both said to me that they would act until they go. My dad is determined to be a lifelong artist.”

Aside from this accolade for “Nebraska” in Cannes, Dern has been nominated twice for an Academy Award. He co-starred in “The Trip,” “The Great Gatsby,” “Coming Home,” “The ’Burbs” and “The Hateful Eight.” He’s amassed more than 150 credits.

Not bad for “the fifth cowboy from the right.”