Hart said after having her youngest son Tucker in late 2012, she waited to drop the baby weight because she wanted to bond with her child first before hitting the gym and dieting.
Now, Tucker and his two older brothers, Mason, 8, and Brady, 6, help Hart keep the weight off and stay in shape just by being normal boys who like to play outside and keep their mom on her toes at all times.
"Staying active with my boys is so important," she told ABC News. "It's so great to be able to just take them to like the Bronx zoo last week, even walking around and pushing the stroller" helps her stay active.
"I make every day an adventure with my kids, make sure there is something special we can do," she said. "I love it, I feel like I'm a really good boy mom. I love the fact that my boys are out there getting dirty, muddy and catching frogs. I love to snowboard, I love to teach them about reptiles and dinosaurs. I think I'm much more of a boy mom than a girl mom. I don't know if I'd do well with painting, glitter and sparkles. I definitely can't do hair."
With that said, Hart, 38, said getting to the gym is just as important. Not just for the physical benefits, but the mental ones as well.
"I make sure I get to the gym, that's sort of my me time," she added. "I love to go spinning. I love to go for runs with friends, or a yoga class. I use the gym as my me time or my social time with friends. I get to the gym 3 or 4 days a week."
Even Hart's husband Mark Wilkerson is "amazed" by her ability to balance, work, raising their three children and now, the couple has launched a boy's clothing line -- King if Harts.
"I'm constantly amazed with her ability to keep going, she never stops, never," he said.
Hart said she found a whole in the boy's clothing market when she and her husband couldn't find things for their three boys. King of Harts will offer jeans, t-shirts and even jackets, all made locally in the US. She added the dream is to eventually have a girl's line as well.
"The dream is to go and do a Queen of Harts -- we are going to grow slowly, it's a learning process," she said.
Hart also just directed an untitled Christmas movie, starring Barry Watson, set to come out later this year. Stepping behind the camera is something she definitely wants to do more of in the near future.
"It's so creatively fulfilling, I love the story aspect of it," she added.