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SHE'S 47!

Courteney Cox 47

How she eats "I'm on a low-carb diet," the Cougar Town star has told PEOPLE. "I drink a lot of coconut water. I don't drink caffeine. I do drink decaf coffee-but it has to be with Coffee-mate Carnation fat-free vanilla milk."

Her exercise routine "I'm doing the Tracy Anderson workout. I love it. It's two parts: dance aerobics and toning. I've seen a big change in my body." Her food weakness "If I indulged, it would be with eggplant lasagna," she says.

SHE'S 44!

HALLE BERRY 44

How she does it: When the actress typically hits the gym, "We do high-intensity cardio and strength training for about an hour three to five times a week," says longtime trainer Gunnar Peterson. "I don't think any 20-year-old can compare to her. She defies age."

Gwen Stefani 41

How she does it "She focuses on high-intensity resistance training," says her trainer Mike Heatlie. Another rule? "I have to work out before noon or I won't do it," the singer told INSTYLE.

Padma Lakshmi 41

Her fast fitness fixes "I keep a jump rope in my bag, so I can skip rope when I have a few minutes," says the Top Chef host, who also occasionally skips the elevator. "There's always a set of stairs you can use for a quick workout."

Demi Moore 48

Her new workout "My husband [Ashton Kutcher] and I have taken up Bikram yoga, where you sweat like crazy," she told PEOPLE last year. "She wants to preserve her arms, stomach, lower body," adds trainer Greg Jon-Jou Roche, who worked with Moore.

Jennifer Aniston 42

How she does it "I do yoga at least four times a week," the Horrible Bosses star, who recently won the Decade of Hotness award from Spike TV, told PEOPLE in February. "I have Mandy [Ingber's] DVD, so I pop that puppy in and follow it."

Her guilty pleasures "Pizza and Mexican food are my weakness," Aniston admits. "You have to have chips and salsa every now and then. You just have to!"