The star, 40, shared a post-workout selfie on Instagram during the COVID-19 lockdown and her exercise routine is clearly paying off.
Wearing a cropped top and tiny shorts Jessica posed for the mirror selfie which showed off her lean physique.
Her abs and legs looked incredibly toned and there was a glimmer of sweat across her brow.
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"Woke up before all 3 kiddos to get my steps in and spend time with me, myself, and I," she wrote. "Move move move for your own mental health."
Jessica - who shares three children, Maxwell, eight, Ace, seven, and Birdie, one, with her husband, Eric Johnson - opened up about her body image, her mental health, and her weight in her memoir, Open Book.
She revealed she became addicted to diet pills after being told by a record label to lose 15 pounds when she was 17-years-old.
Jessica works hard to stay in shape
Jessica - who dropped to 103 pounds - admits she then took them for twenty years.
However, her latest body transformation has been done in a healthy way, with the help of celebrity personal trainer, Harley Pasternak.
Jessica weighed 240 pounds after birth of her third child
He told E News: "It had to be more than just getting back from her baby weight, but how do I keep whatever I am doing now forever. That's why we are not a big fan of doing any extreme diet or radical forms of exercise."
Jessica - who weighed 240 pounds after Birdie's birth - worked up to 14,000 steps a day and worked out with a trainer three times a week, but has continued to exercise by herself from her LA home during the coronavirus quarantine.
Jessica is proud to fit into her decade-old jeans
When it comes to her diet Harley encouraged Jessica to eat three, healthy, protein-filled meals and two snacks per day.
Rather than deprive her entirely of the foods she loves they worked on her having several cheat meals throughout the week.
Jessica also quit alcohol three years ago and has never looked back.
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