Every morning, Mamie Van Doren walks down to the beach near her home in Southern California and sits on the same rock with her feet in the Pacific. “It kind of heals me,” she says.

At 95, she has outlived just about everyone. Her memoir, You Thought I Was Dead: My Life of Celebrities, Sex, and Champagne, is out now from Simon & Schuster, and she already has started the next book — about Marilyn Monroe, who would have turned 100 this month.

Mamie — rhymes with “pay me” — knew her before she was Marilyn. To her, she is still Norma Jeane Baker, a teenager who defended a stranger at the Ambassador Hotel pool during the war years in Los Angeles.

By the 1950s, Hollywood had repackaged them both as blond bombshells and set them against each other — Van Doren was Universal’s answer to Fox’s Monroe, measurements printed side by side in fan magazines. Monroe died in 1962. Van Doren kept going. She has stories she has kept quiet for decades — about Howard Hughes, Tony Curtis, Jack Webb and others. Some, she is telling fully for the first time. She recently spoke with THR.

You’re 95. You seem extraordinary. What’s the secret?