By Michelle Tauber
December 16, 2013 12:00 PM

Julia Roberts isn’t the kind of actress who stays in character between scenes. Even in the midst of shooting the mother of all dinner table fights with Meryl Streep in the new drama August: Osage County, she kept things light when the cameras weren’t rolling. “Julia would be sitting with other people on these fold-out chairs in the front yard, knitting sweaters,” recalls director John Wells. And if Julia Roberts tells you to knit, well, you’d better knit. “She got me to put together a sweater I had put down 10 years ago,” says costar Julianne Nicholson. “She makes you feel like you’ve got to finish something.”

Oscar winner, mother, needle-wielding motivator: At 46, the once-and-forevermore Pretty Woman has found her sweet spot as a really-and-truly hands-on mom (see: three home-cooked meals a day) who can afford to be choosy with her roles. Twenty-five years after her iconic smile dazzled audiences in Mystic Pizza, the superstar who spent much of her 20s and 30s in the spotlight with a series of high-profile romances and a whopping $3 billion in box office receipts is now ensconced in what she describes as “the harbor of my life” with twins Hazel and Phinnaeus, 9; son Henry, 6; and her husband of 11 years, Danny Moder, 44. But the right part can draw her out, and she is earning critical raves for her turn opposite onscreen mom Streep in August, which opens on Dec. 25. “I’ve never worked so hard in my life, and I have given birth to three children,” she says of the film’s two-month Oklahoma shoot. Although “she makes certain the hours are such that she can still be a mother,” says Wells, Roberts admits that she was painfully unaccustomed to being away from her husband and kids for such long stretches. “I felt untethered. I was lost, walking into walls; I couldn’t sleep. I missed my family,” she recently said. “I realized that I’m not that person anymore – that person who used to travel the world.”

These days she’s an overachieving mom who sews sleeping bags for her daughter’s dolls, leads school trips to museums and whips up baked kale chips at her eco-friendly, ocean-view home in Malibu and her getaway in Taos, N.Mex. “It’s my privilege and honor to cook three meals a day for my family,” she told Marie Claire. Since settling down with Moder, a cinematographer she met while filming The Mexican in 2000, Roberts has often expressed her contentment with the man who “makes me feel my most comfortable self,” as she told Oprah Winfrey. During the August shoot, Moder kept things running smoothly at home. “More than anything, the singular man who got me out of the house and on a plane to Oklahoma to do this [movie] – and it made me believe in myself in a whole brand-new way – is my husband,” she said in a speech at the Hollywood Film Awards on Oct. 21.

Although she still owns every red carpet she appears on, Roberts has always preferred bare feet to sky-high heels – even doffing her shoes to present good friend George Clooney with a recent award – and sticks to her routine of school runs, yoga and soccer games. “I’m always the first one up in the morning, getting things ready for my family,” she says. “In that kind of half-light, I just take a moment to feel gratitude or meditate or whatever to bring myself into consciousness. I need the balance of starting each day very sure of who I am and my place in the world.”

It’s a long way from where she started, growing up in a middle-class suburb of Atlanta as the third child of onetime actors and playwrights Betty Lou and Walter Grady Roberts. Playing the firstborn child of Streep’s character in August, “I learned I liked being the oldest,” says Roberts, whose brother is actor Eric Roberts, 57, and sister is Lisa Roberts Gillan, 48, her sometime producing partner. When it comes to getting older in Hollywood? “I’m trying to up my game as an aging supermodel,” she recently joked. A current face of Lancôme, she credits their products with helping keep her skin youthful and says, “I haven’t done any tinkering under the hood, which is important. I feel I’m best with a natural look.”

As for winning an Oscar, “I highly recommend it,” jokes the actress, who nabbed hers for Erin Brockovich in 2001. But mostly she’s content to find joy in her life away from the cameras. “We all love the way she looks, laughs and smiles,” says her August costar Dermot Mulroney, who first teamed with Roberts in 1997’s My Best Friend’s Wedding. “What I’ve seen is that she has a private side. I see her smile with family and her husband in a way that you guys don’t see onscreen.” So while she’ll continue to work in roles that resonate for her – including the upcoming HBO film The Normal Heart, in which she plays disabled AIDS researcher Dr. Emma Brookner – her focus is firmly on her family. “That’s all there is,” she says. “Fame is a summer breeze that comes and goes. But to have a bedrock of knowing who you are, that’s what it’s all about.”