"She didn't give a s--- about getting old," her friend Frank D'Angelo tells PEOPLE.

After falling out of the Hollywood spotlight relatively early in her career, Margot Kidder continued to lead a happy, productive life, appearing in a number of small films, advocating for mental health awareness, fighting for political causes and enjoying small town living in Montana.

The actress, who died on Sunday at her home in Livingston, Montana, at the age of 69, “didn’t give a s— about getting old,” her friend Frank D’Angelo, who directed her in her final film, told PEOPLE.

“I think she had enough of Hollywood because in Hollywood, her motto was, when you turn 30 and if you don’t do stuff with producers — and I’m being cordial here — you’re not going to be in any movies,” D’Angelo added.

Kidder rose to fame in 1978 for her role as Lois Lane in Superman opposite Christopher Reeve. She and Reeve would go on to appear in three more Superman movies together, with the final film premiering in 1987, but both had difficulty finding quality work after finishing the franchise.

Her struggle with bipolar disorder, which became highly publicized after a 1996 manic episode left her homeless for a time, also likely contributed to her career’s decline. After receiving treatment, Kidder went on to become a lifelong advocate for mental health awareness. “She was completely open,” D’Angelo said of her struggles with mental health. “She was homeless and she didn’t regret that. To her that was an experience.”

Superman - 1978
Margot Kidder and Christopher Reeve.
| Credit: Allstar/WARNER BROS/REX/Shutterstock

Kidder’s openness to new experiences could also cause problems later her in life, according to Cara Wilder, actor and co-founder of Bozeman Actors Theatre. “She always took in people in her house in Livingston because she had a big house and plenty of room but she got into trouble because people took advantage of her,” she explained.

Wilder continued, “She didn’t live her life terribly carefully I don’t think. She needed to make money in these last few years so she would go to [fan] conventions where they paid her a lot of cash to sign things.

After recovering from her breakdown in 1996, Kidder began taking on a number of smaller roles in various off-beat projects. “I’m not choosy at all! I’ll do practically anything,” she told The Advocate in 2008. “I’m the biggest whore on the block. I live in a little town in Montana, and you have to drag me out of here to get to L.A., so I’m not readily available. But unless it’s something sexist or cruel, I just love to work. I’ve done all sorts of things, but you just haven’t seen them because they’re often very bad and shown at 4 in the morning.”

She made a total of five films with D’Angelo, including her final film, 2017’s The Neighborhood, and 2016’s The Red Maple Leaf, which featured a star-studded cast including James Caan, Kris Kristofferson and Mira Sirvino. “Everybody on the set loved her. Everybody gravitated to her,” D’Angelo told PEOPLE.

Outside of acting, Kidder continued to be politically active throughout her later life. She was the Montana State Coordinator for Progressive Democrats of America as recently as 2009, and in 2011, she and dozens of other protestors were arrested while protesting the Keystone Pipeline.

August 9, 2010-MARGOT KIDDER-Iconic actress Margot Kidder, poses for a photo Monday August 9, 2010 i
Margot Kidder in 2010.
| Credit: Tara Walton/Toronto Star via Getty Images

She was a vocal supporter of Bernie Sanders’ presidential bid and hosted a dinner event by the Yellowstone County Democrats in Billings, Montana titled “Billings for Bernie.” When Hillary Clinton was chosen as the Democrat’s candidate for president at the 2016 Democratic National Convention, she wrote, “I am not an American tonight … I reject the words I voiced at my citizenship ceremony.” (Kidder, born in Canada, became an American citizen in 2005).

“We were very politically active so we had that in common,” Wilder told PEOPLE. “She absolutely led an unapologetic life. She had no qualms about being who exactly she was, saying things very much out loud wherever she was.”

Wilder noted that Kidder “also went to Standing Rock” in North Dakota, where she protested the Dakota Access Pipeline. “This woman, who was that old, going by herself to stand with these people. She wouldn’t let her health or her finances stand in her way of what she felt she needed to do to help people.”

Kidder, whose cause of death has not yet been made public, is remembered by her daughter Maggie, 41, with whom she had a “rocky relationship,” Wilder said.

“It’s a shame how people remember her, as either Lois Lane or the crazy actress, she was so much more than that,” Wilder added. “She was such a caring person, I know she had difficulty with some members of her family but I didn’t know her that way at all.”