Jessica Simpson in Bathing Suit Has "Neon Energy"

Jessica Simpson is modeling Kim Kardashian’s swimsuits. The singer, actress, and entrepreneur shows off her slimmed-down figure in a neon green swimsuit in one of her latest social media posts. “SKIMS Swim + @Jessicasimpsonstyle Shoes = Neon Energy,” she captioned the Instagram snap. How does the mother of three keep herself physically fit? Read on to see 5 ways Jessica Simpson stays in shape and the photos that prove they work—and to get beach-ready yourself, don't miss these essential 30 Best-Ever Celebrity Bathing Suit Photos!

1. She Went to a Nutritionist

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Jessica maintains that her weight loss after baby number three primarily had to do with her diet. “I went to a nutritionist, and I needed to get my eating habits right,” she recently told Extra.

2. She Doesn’t Weight Herself

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Jessica’s trainer, Harley Pasternak told People that Jessica doesn’t pay attention to the number on the scale. “I never work with scales. My work with her is more about the habits she’s created and kept up. And as a byproduct of doing these habits, she lost 100 pounds,” he said. She recently told Today that she doesn’t weigh herself. "I have no idea how much I weigh," she said. "I just want to feel good and be able to zip my pants up. If I don't, I have another size. I have every size."

3. She Works Out

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Jessica’s sessions with Harley Pasternak are no joke. At one point she was doing 45-minute sessions three days a week, consisting mostly of strength and weight training exercises. She also gets her steps in with the help of activity trackers. As she embarked on her journey, her goal was 6,000 steps per day, eventually building up to 14,000, per E! News. “It’s a social thing that she can do with her kids," Pasternak said.

4. She Pushes Herself

Jessica pushes herself, even when she doesn’t want to work out. “First day back at it and I’m already hurtin’ and feelin’ real dramatic about being sore. I have been craving this, but procrastinating. One work out and I am determined to not let myself down. Although I will be eating a brownie to give myself some points!” she captioned an Instagram post of herself on the treadmill.

5. She Does Yoga

Jessica also does yoga, which is a great workout according to Harvard Health. “Researchers found that people who practiced yoga for at least 30 minutes once a week for at least four years, gained less weight during middle adulthood,” they said. “People who were overweight actually lost weight. Overall, those who practiced yoga had lower body mass indexes (BMIs) compared with those who did not practice yoga. Researchers attributed this to mindfulness. Mindful eating can lead to a more positive relationship with food and eating.”