Jennifer Aniston showed off her smoking hot bikini body while celebrating her 41st birthday in Cabo San Lucas, Mexico, over the weekend. Want to emulate her flat abs and toned booty?

Marco Borges (who has whipped Beyonce Knowles and Gwen Stefani into shape) and trainer Joy Di Palma (creator of Core Conditioning Cross Fit).

BODY"Jen looks extremely long and lean," Borges tells Us. Her routine includes cardio workouts, 4 to 5 hours of yoga a week with Mandy Ingber and high-intensity sessions with Tracy Anderson (who has sculpted the bods of Madonna, Gwyneth Paltrow and Aniston pal Courteney Cox).

To get her defined muscles, Aniston incorporates yoga positions such as planks (hold a pushup without moving to focus on your abs) and crescents (go into a deep lunge, clasp your hands together and reach straight above your body to strengthen your back) for up to 60 seconds each.

To look like her, Borges recommends toning up by doing an hour of yoga two days a week, and slimming down with a combination of resistance-training and cross-training techniques like running, spinning classes or jumping rope for 30 minutes three times a week.

To replicate a lean body -- especially in your 40s -- you'd have to eat an "extremely clean diet" that is high in protein and consists of many small meals to keep the metabolism going, Di Palma says.

"People who just do yoga don't look that great," Di Palma explains. "It takes eating right to really get that body."
Foods to incorporate into your diet?Lean carbs like "yams, sweet potatoes, brown rice and oatmeal," she tells Us. For snacks, she recommends "peanut butter, cottage cheese and fruit, and a handful of almonds."