Jessica Simpson reportedly "spends half the day" in the gym.
The Weight Watchers spokesperson, who has lost more than 60 lbs. since giving birth to her second child, Ace, last June, has worked extremely hard for her toned figure and runs six miles almost every day.
An insider told Life & Style magazine: "Jessica has gotten her best body ever. She truly feels like she's in better shape than she was in her early 20s.
"She set out to get the best body of her life - and she's accomplished it."
The 33-year-old blonde beauty, who is gearing up to marry fiancé Eric Johnson in Santa Barbara, California in July, with whom she also has two-year-old daughter Maxwell, works out "three to five times a week" with her personal trainer, Harley Pasternak, and spends a lot of her free time on the treadmill.
The source said: "She'll watch TV on it, talk on the phone. Jess probably spends half the day there... She's incredibly proud of the way she's stayed on track."
Jessica recently insisted she had no regrets about gaining weight, as she learnt a lot from the experience.
She said: "I fluctuate, I'm a woman. I feel like we all need to enjoy life. If I'm five pounds heavier or 50 pounds heavier or five pounds lighter, I don't think that should define who you are."
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