Simpson, 33, who lost 50 pounds before marrying Eric Johnson in California earlier this month, took to Instagram to show off her slender figure and credited her time in the gym for boosting her body confidence.
Simpson, who has two children with Johnson, posted a shot of herself and a friend wearing revealing swimsuits and heels on the picture sharing site as she celebrated her sister, Ashlee's bachelorette party.
"Oh yea girl...We are proud to be in our bathing suits!! hardworkpaysoff, workoutpartnersforlife," she wrote.
Although she is more than happy to show off her toned body, Simpson is said to be planning to lose even more weight after becoming an exercise addict.