03/16/2013 at 03:00 PM EDT
says she manages to keep her shape by staying constantly on the go with her four children and merging her busy schedule with theirs.
"It's very hard to find time obviously to work out. I'm like a mom and dad in one," says the über-fit supermodel, 39, who separated from husband Seal
"When I go shopping I put on my sneakers and my [fitness] clothes. I run through the store or I take the dogs and the children and I go up the canyon or I go into the backyard and I jump with my kids on the trampoline, so I try to put the exercise into my daily routine," she said at Thursday's launch of her Heidi Klum for New Balance Collection at Lady Foot Locker in Culver City, Calif.
Klum said she cooks healthy at home, but also doesn't dine on the pasta and pizza her kids love to order when they eat out.
While she gained 45 pounds with each of her pregnancies, "I have never really dieted," Klum said, noting, too, that she pays attention to what she consumes.
"You have to really look into it and understand it and understand food and what It does for your body and what it needs and doesn't," she said.