The best way to get over a breakup? Breaking a sweat.

On Tuesday, Jessica Simpson - who was dumped by Tony Romo on the eve of her 29th birthday July 10 - had a personal-training session in West Hollywood. Clutching a bottle of Smart Water and wearing short workout shorts, she smiled for photographers.

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It was one of Simpson's first public outings since her split with Romo. (She also enjoyed a girls' night out with pals last Saturday, writing on her Twitter page: "Love my ladies!!!")

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Earlier this year, Simpson underwent scrutiny for flaunting a fuller figure an an outdoor concert.

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A source tells Usmagazine.com her relationship with Romo caused her to pack on a few extra pounds. "Tony was always threatening to break up with her, and it would send her into a panic," says the source. "That's why she's gaining so much- it's emotional eating."

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Now Simpson wants to get back in shape, sources tell Us. She is set to shoot The Price of Beauty, a VH1 reality show that has her traveling the world to learn about body image. The show debuts in 2010.

In the meantime, Simpson's personal trainer, Harley Pasternak, is hosting a MSN Web series, Focus on Feeling Better, to offer health and wellness tips and tricks.

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