Her secret? She takes a lot of walks!

Insiders revealed to E! News that Kunis hasn't spent her time sweating in a gym and instead, has been "taking Wyatt on walks around her neighborhood" as much as possible. She also takes long walks with her fiance.

"It's very private and peaceful," the source said of the "That '70s Show" alum. "She and Ashton have also taken long walks along the bike path in Santa Monica. Their house has a hiking trail outside of the front door and Mila also loves hiking in the canyon."

During her pregnancy, Kunis confessed to doing a lot of yoga and Pilates workouts but she's apparently ditched her old routine and taken to exercising with Wyatt instead.

"She's been staying close to home with Wyatt," the insider added.

Another workout Kunis recommended is breastfeeding, which she told talk show host Craig Ferguson during a guest appearance on his "The Late Late Show" helped her lose weight.

"Breastfeeding's a great workout! Let me tell you!" she said a few weeks ago on the CBS show.

Kunis was spotted rocking skinny jeans earlier this week, while she enjoyed a day out with her family and her friends. She and Kutcher were seen cooing over their little girl, who seems to have inherited her parents' good looks with her big eyes, brown hair and adorable button nose, according to Daily Mail.

Despite her obviously busy schedule as a fulltime mom and actress, Kunis didn't find the transition to motherhood all that difficult.

"I seem to eat a lot, so that kind of keeps me going through the day. [It's] not too bad," she revealed. "I do love to eat healthy."