June Squibb insists on doing her own stunts.

“I never think of myself as being old,” says the 94-year-old Oscar-nominated actor as she heads to Sundance for the premiere of her new film “Thelma.”

It’s an adventure movie that proves kicking ass isn’t just a young person’s game. In it a grandmother loses $10,000 in a phone scam, prompting her to set out on a treacherous quest to get her money back.

It’s fitting that Squibb, who gets the first starring role of her seven-decade screen career, was willing to perform action scenes that could have left her with titanium hips, because “Thelma” cheekily references and riffs on the gravity-defying sequences of “Mission: Impossible.”

“Tom Cruise jumping out of a plane is as dangerous as my grandma getting onto a bed,” says writer-director Josh Margolin. “I wanted to treat Thelma’s mission with the sincerity and stakes that you would Ethan Hunt globe-trotting to track down the bad guy.”

In one scene, Squibb hijacks an electric scooter and has a vehicular showdown in a retirement home with Ben, played by the late Richard Roundtree in his final screen performance. The two zoom into each other and crash, as Squibb plows Roundtree’s scooter out of the way.

“They weren’t expecting me to do the scooter work,” Squibb says. “They were so worried about me, they thought I was going to kill myself. They said, ‘Just tap his scooter,’ and I thought, ‘Oh, hell,’ and I just cowed into him.”

The storyline is based on a scam phone call that targeted Margolin’s own grandmother, who is now 103. (Luckily, the real Thelma caught on to the ruse before sending money.) Margolin, who previously filmed his grandma for a series of short documentaries, inserted some of her unscripted quotes into the movie, and admits that he put “a very solid amount” of himself into Thelma’s grandson, Danny, played by “White Lotus” breakout Fred Hechinger.

“He’s heaven,” Squibb says of her 24-year-old co-star, adding that since “Thelma” wrapped Hechinger has stopped by her Los Angeles home three or four times to hang out. “We have lunch or dinner or whatever is happening. He’s a really good friend now.”

Margolin screened the film for his grandmother ahead of its Jan. 18 Sundance premiere. “She was very moved by it,” he says. “The thing that weirded her out the most is when June says, ‘I’m Thelma Post,’ because that is just my grandma’s name. She was sort of haunted by that.”

Squibb hasn’t yet met the real Thelma, which she calls “one of the sorrows of my life,” but the two have traded television recommendations via Margolin.

“We’re both TV cop fans,” Squibb says. “I recommended her ‘FBI’ and she recommended ‘Blue Bloods.’ It’s a great show!”

While “Thelma” — which also stars Parker Posey, Clark Gregg and Malcolm McDowell — is in part a buddy comedy, its emotional core lies in the relationship between grandmother and grandson. As Thelma adjusts to living solo after the death of her husband, Danny constantly worries for her safety. She embarks on her mission alone to prove to him — but also to herself — that she can get along on her own. It’s a feeling that resonates with Squibb more these days.

“At some point it changes — the way people treat you,” Squibb says. “They want to take care of you, which is lovely, and sometimes I just let them take care of me. But other times you think, ‘I can do this and I’m fine.’ They want to lend an arm or a hand. So you do it — you take an arm, you take a hand. But I am still independent and able to live a life of my own.”

At the end of the interview, I ask Squibb what’s next on her docket. She breaks into a big, warm laughter: “As you know, I’m 94 years old.”

Still, she rattles off a busy schedule. She’s flying to Sundance to promote “Thelma,” and then to New York on Feb. 19 to shoot another movie. Just hours before our call she was offered to play a vampire on TV, a prospect that greatly excites her. And she’s lending her voice to Pixar’s “Inside Out 2,” due in June.

“It’s a surprise to me, too,” Squibb says, chuckling, “but I am still working.”