(Photo Credit: nicolechavezstyle/Instagram)

Jessica Simpson is doing something right!

Just a few months after giving birth to her son Ace, the fashion mogul, 33, flaunted her post-baby body in a one-piece swimsuit.

"Guess which mama I get to play dress up with today?" Simpson's stylist Nicole Chavez posted on Instagram, along with this shot. Simpson retweeted the post, and added a smiley face.

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The mother of two has reason to be proud.

"I didn't gain as much weight in my second pregnancy, but I still gained a lot of weight," the Weight Watchers spokeswoman told ABC News last month. "Any woman, dealing with their body after pregnancy, you look at yourself and you're like, 'What just happened to me?'"

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To get back in shape, Simpson has been hitting the gym four times a week and tries to log 12,000 steps every day using a pedometer. She's also eating cleanly.

"An indulgence for me is like, ice cream, so I can have a Skinny Cow for four points, and I know that that'll be the sugar that I want that day," she said. "Today we just had an eight-point lunch, and it was a faux spicy chicken sandwich from Wendy's but it wasn't from Wendy's. We made it in a healthy way!"