Heather Locklear on Life at 60, Love and Her New Movie: 'I'm in a Great Place Now'

Heather Locklear is returning to acting for the first time in five years — and the project couldn't be more special to her.

The Melrose Place alum, 60, stars in the upcoming biopic Don't Sweat the Small Stuff: The Kristine Carlson Story. Premiering Saturday on Lifetime, the film takes its title from the book series co-authored by Kristine and her husband, Dr. Richard Carlson. After he died unexpectedly at 45, she continued to spread his message in her own books.

The movie, executive produced by Meghan McCain, follows Kristine (Locklear) as she grapples with the death of her spouse (Jason MacDonald). The sudden widow and mother of two finds herself navigating unchartered territory while dealing with pressure to become the new face and voice of the Don't Sweat the Small Stuff brand.

"There was so much synchronicity," Locklear tells PEOPLE in this week's issue of her ties to the film. "[Kristine's] husband, Richard — his first love was a woman named Janie Sinclair. She was my roommate in college [at UCLA]. I'm like, 'This is crazy.'"

"The first time I met Kristine, we spent the night at her home," she continues. "And then she came for my 60th birthday and stayed with me. She's now one of my best friends."

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For Locklear, Kristine's story is "about love and loss."

"They're just simple ideas," she says. "And I think maybe during the pandemic we got simplified. It's about living in the moment. And really it's all about love."

Kristine's example of resilience resonated deeply for Locklear, who recently marked two and a half years of sobriety. These days, the actress says she's "in a great place" as she enjoys life with daughter Ava, 24, and fiancé Chris Heisser, her high school boyfriend. (The two graduated from Newbury Park High School in Los Angeles together in 1979!)

She and Heisser, who were on and off during Locklear's struggles in recent years, got engaged last April as they were celebrating her first year of sobriety.

A year and a half later, Locklear says she's content in the moment regardless of whether the couple ends up walking down the aisle together.

"I'm like, 'You're my man for the rest of my life, whether we get married or not,'" she tells PEOPLE. "[A wedding] is so not important. We're together, and we love each other and support each other. And really that's all that matters."

Last month, she and Heisser both celebrated their 60th birthdays, a milestone Locklear says she doesn't "give a hoot" about.

"I've always loved getting older because it means I'm alive," she says. "I'm so grateful. I don't really give a hoot. I don't give a hoot about how I look. My parents still love me. My daughter loves me."

"[Heisser], because his birthday is two days before mine, said, 'Can you believe we're turning 60?' And I said, 'I can't wait,'" she adds. "I feel young. I'm a young 60. It's all about perspective."

Don't Sweat the Small Stuff: The Kristine Carlson Story premieres Saturday at 8 p.m. ET on Lifetime.