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JENNIFER LOPEZ
BIRTHDAY: JULY 24

COMPETED IN A TRIATHLON

HOW SHE WORKS OUT
With her milestone birthday approaching, Lopez says she was "very specific" with trainer Gunnar Peterson: "I told him, 'I want to be in the best shape of my life!'" To get there, the star has been hitting the gym three times a week for an hour, doing side lunges with a 20-lb. medicine ball, as well as "intense" cardio on the elliptical and stationary bike. "She's a hard worker," Peterson says.

HOW SHE EATS
Lopez works just as hard when it comes to her diet, sticking to 1,400 calories a day thanks to the meal delivery program Freshology. Her faves include provolone and roasted-pepper frittatas for breakfast, grilled shrimp salad for lunch and pan-roasted salmon for dinner.

HOW SHE FEELS ABOUT TURNING 40
"I don't talk about it," she says with a laugh. "And I don't let [husband] Marc [Anthony] talk about it either!"

JENNIFER ANISTON
BIRTHDAY: FEB. 11

YOGA LOVER

HOW SHE WORKS OUT
Four times a week, Aniston practices yoga with Hollywood guru Mandy Ingber, warming up with a 22-minute treadmill run before her hour-long session. She even does yoga on vacation, signing up for classes when at the One & Only Palmilla Resort in her beloved Cabo San Lucas, Mexico.

HOW SHE EATS
When dining out, Aniston usually orders such lean proteins as sole and salmon with veggies on the side (two faves: asparagus and sauteed spinach), or salads with chicken or grilled shrimp. And when it comes to alcohol, Aniston skips cocktails in favor of lower-calorie white wine or champagne.

HOW SHE STAYS MOTIVATED
A strong emotional support system goes a long way. "She's got a lot of light, a lot of joy around her," says close friend Sheryl Crow, which helps make Aniston "comfortable with aging." Adds Suddenly Susan actress and pal Andrea Bendewald: "She has always known how to have a good time and live life to the fullest."

GWEN STEFANI
BIRTHDAY: OCT. 3

LIFTS LIGHT WEIGHTS

HOW SHE WORKS OUT
"Yoga or Pilates—they don't work for me," Stefani told Elle UK. Instead the singer and mom of Kingston, 2, and Zuma, 7 months, works out four times a week. Her trainer Mike Heatlie recommends cardio intervals and training with weights.

HOW SHE EATS
Heatlie advises his clients to eat six small meals a day of "lean meats, sweet potatoes for carbs and lots of green vegetables," he says.

CATHERINE ZETA-JONES
BIRTHDAY: SEPT. 25

SHE'S AN AVID GOLFER

HOW SHE WORKS OUT
Living in Bermuda has its perks when it comes to staying in shape. "I do a lot of swimming, both in the ocean and in the pool," says Zeta-Jones. Another favorite pastime? Golfing with husband Michael Douglas. "It's a great sport," she says. When she really has to tone up, however, "I've got to drag myself to the gym," she admits, "but when I finish it, I enjoy it."

HOW SHE EATS
Sticking to a diet she calls "sensible" means "three meals a day; no snacking" says a friend, adding, "sweets aren't really her thing." No, she'd prefer fish. The actress is a huge fan of "smoked salmon sandwiches with potato chips crunched inside," she told PEOPLE. "And fish and chips if I [didn't] put on weight."

ELLEN POMPEO
BIRTHDAY: NOV. 10

BRINGS MEALS TO THE SET

HOW SHE WORKS OUT
"I'm a natural waif," admits Pompeo. And so her three-day-a-week workouts with personal trainer Gregg Miele aren't about keeping off weight; they're about "looking muscular" and "building endurance," she says. To achieve both Miele puts her through 60-minute sessions that mix stretching, high-knee runs and cardio, all done to blasting hip-hop music. "It kills me!" she says. "But I love that."

HOW SHE EATS
"Maybe because I play a doctor, I eat really clean foods," says the Grey's Anatomy star. That means no white flour or sugar, and lots of berries, yams and greens. "I'm really good; I take all my food to work," she says. One thing she won't be doing: going vegetarian. "I tried, but I get too skinny, and people think I'm anorexic," she says. "It just doesn't suit my body type."

HOW SHE STAYS MOTIVATED
"It's pretty boring during the week," Pompeo admits. "But then the weekends are when I pig out." Her favorite indulgences: pizza, lasagna, salami and red wine.

A Day in the Life of Ellen's Diet
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  • Contributors:
  • CONTRIBUTORS Amy Elisa Keith,
  • Michelle Tan,
  • Charlotte Triggs,
  • with Julie Jordan,
  • Bethany Lye,
  • Lesley Messer,
  • Alyssa Shelasky,
  • Jeffrey Slonim.