Meryl Streep didn’t even ask to read the script before signing on to join the cast of Big Little Lies‘ second season. “That first season blew me away,” explains Meryl about the hit HBO drama. “Everything about it: the writing, the depth of the performances, the style, the music, the whole world. And I couldn’t wait to see where it was going to go.”

With her 70th birthday coming up on June 22, Meryl has learned to trust her instincts. They’ve rarely led her stray; she’s the most nominated actor in Oscar history (21 and counting!) and could win her fourth Emmy for BLL. The key to her professional success? “I’m curious about other people,” she says. “That’s the essence of my acting. I’m interested in what it would be like to be you.”

Despite all of the acclaim she’s received over the years, she’s managed never to take herself too seriously. “She is just not a pretentious person,” an insider exclusively tells Closer Weekly in the magazine’s latest issue, available now. “She’s spontaneous and playful, and she tries to surprise everyone.”

Big Little Lies Cast Meryl Streep
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Meryl has found longterm happiness in her personal life with her husband, sculptor Donald Gummer, whom she married in 1978. A calm and levelheaded presence, he’s helped Meryl put life into perspective. “You just have to keep on doing what you do,” she says. “It’s the lesson I get from my husband. He just says, ‘Keep going. Start by starting.'”

They’ve tried to pass along this wisdom to their kids: musician Henry, 39; actresses Mamie, 35, and Grace, 33; and model Louisa, 28. Meryl became a grandma for the first time when Mamie gave birth to a son earlier this year, and she says her family has always been the primary influence on her career: “Every single decision I make about what material I do, what I’m putting out in the world, is because of my children.”

Even when she’s weathered difficult times — like the tragic death of her boyfriend John Cazale from brain cancer at 42 in 1978 — she’s found meaning in the struggle. “I learned what really is important,” she says. “I found what is true and what’s not worth pursuing.”

Big Little Lies Meryl Streep Cast
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And rather than resting on her laurels, she continues to try new things, whether it’s doing musicals like Mamma Mia! and Mary Poppins Returns or taking her first-ever TV series role on BLL. “She’s naturally clever, loves her craft and will never stop acting,” the insider says. “Taking on new challenges is a part of her being. She’s invigorated with every project, and BLL was no different.”

Meryl’s commitment certainly impressed her costars. “I love that she likes to work — she works so hard, and acting is still her love and passion,” gushes BLL‘s Nicole Kidman. “She’s such a pro, and she’s so transparent with her vision and all her emotions in her work. Every day she inspired us.”

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