Sarah “Fergie” Fergusonhas weathered countless ups and downs during her nearly 40 years in the spotlight, and today she says she isat peace with her past.

“Someone asked me, ‘If you were an astronaut and you could take all the pressure off you, would you leave behind Fergie and Sarah and the Duchess and your past mistakes and failings?'” the Duchess of York, 61 — who became popularly known as “Fergie” in the 1980s after she married the Queen’s second son,Prince Andrew—tells PEOPLE exclusively in this week’s cover story.

“And I said, ‘What are you talking about? They’re all my friends.’ I made friends with past mistakes. I made friends with Fergie. She didn’t know any better. And then Sarah. That’s why we experiment. How is it that we’re meant to be knowledgeable when we don’t know? My Fergie, my Duchess, my Sarah: They’re all good people.”

Sarah Ferguson in PEOPLE Magazine.David Burton

sarah ferguson

For the full exclusive interview with Sarah Ferguson, Duchess of York, pick up this week’s issueof PEOPLE, on newsstands now

Much of her self-discovery came as she wrote her debut novel,Her Heart for a Compass, a sweeping coming-of-age story due August 3 about one of her ancestors, Lady Margaret Montagu Douglas Scott.

Sarah Ferguson’s new novel, Her Heart for a Compass.

her heart for a compass by sarah ferguson

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“In researching her, I found out more about my own DNA, and I found that resilience and courage and sense of hope and optimism,” says the Duchess, who is mom toPrincess Eugenie, 31, andPrincess Beatrice, 32, and a new grandmother toEugenie’s 5-month-old son August. “I am a full-blown Celtic redhead, and that comes with a great enthusiasm for life, great spontaneity, and also — you just fight on.”

From left: Princess Beatrice, the Duchess of York, Prince Andrew and Princess Eugenie in a family photo shared on Instagram.Sarah Ferguson/Instagram

sarah ferguson and family

Now, as she steps out for the release ofHer Heart for a Compassamid her ongoing charity work withSarah’s Trust, she is embracing her new chapter — and her authentic self.

“I have to be aware that trying to be perfect is no longer necessary,” says the Duchess, “and that actually being Sarah is just enough.”

Listen below toour daily podcast PEOPLE Every Dayfor more onPEOPLE’s cover story interview with Sarah ‘Fergie’ Ferguson.

source: people.com