Kate Middleton and Prince William's three children, Prince George, Princess Charlotte, and Prince Louis, always seem happy and well behaved when out in public. That certainly has a lot to do with William and Kate's co-parenting style.

But what exactly goes on when the cameras are not rolling? An inside source recently told "People" that Kate typically manages the children's schedules at home. She is deeply involved in every part of the kids' day," the source said.

The source also revealed three specific rules that Kate follows regarding parenting. We suspect all parents can pick up on some of these tips.

Rule #1: Encourage children to get outside

In an interview on the "Happy Mum, Happy Baby" podcast last year, the host asked Kate when she was happiest. Kate replied, "When I'm out in the country with my family and we're all dirty and polluted."

The Duchess continued with her own childhood memories of family walks and having her parents cheer her on at sports games. She hopes to create similar memories for her three children.

"What I want my children to remember are the moments with me as their mother and going to the beach as a family and getting soaked and filling their boots with water," Kate said.

"Not a stressful family where we try to do everything and not a single thing goes right."

Rule 2: Make time for family fun

William and Kate always have family activities (both indoor and outdoor) for their children. For example, in a video released in April to celebrate their 10th wedding anniversary, the Cambridges can be seen climbing trees, roasting marshmallows, and climbing dunes on the beach.

The family's fun-loving nature is also reflected in the children's Christmas gifts this year. In addition to plenty of games and books to play indoors, the two boys received camping equipment and Charlotte received a children's video camera.

Rule 3: Be an "ongoing parent"

"Kate likes to keep things mundane," a source told People. This includes practical parenting habits like eating breakfast together and picking up her children from school in the afternoon.

At night, after the children have gone to bed, William and Kate relax together. A family friend says, "William brings Kate a gin and tonic." They care for each other, but in different ways."