"The ultimate beauty secret for a woman getting older is, Don't be too thin! It is always better to have a little meat on your bones. When you are just muscle, you end up being gaunt in the face, and that makes you look older by five or 10 years," Klum tells the mag.
But that doesn't mean getting lazy and avoiding workouts.
"One of the best parts about season eight of 'Project Runway' being taped in New York City was that I went running every morning. I had a watch that counts the miles and the little thing you put on your shoe that measures each step. Over seven weeks, I ran 120 miles! I don't love running, but I do like to see everything getting tighter and toned."
The supermom of four says right now she isn't afraid of the aging process.
"I don't have anxiety about it, so I'm not running to get Botox. Maybe that will change, but I don't think so. I feel comfortable in my skin and comfortable with aging, so I think it's OK that I get wrinkles," she admits.
Of course part of not stressing about life has to stem from her happy five-year marriage to singer Seal, who she says keeps her grounded and fulfilled.
"Part of why we're so good together is that, in a lot of ways, we're opposites. I'm speedy, and I don't like sitting still for long. My husband is the most patient person I've ever met. He can explain something to the children for hours, and I will just say, 'OK, this is how it is.' We're both really creative people. We may have some different passions, but we love and respect and trust each other."
Part of keeping their magic alive is making time for each other, and Klum is constantly brainstorming new adventures for the two of them.
"I'm always thinking about what will make my family happier... What can I do with my husband? Can we steal away to Vegas for the weekend? Is there a play we want to go see?
"You shouldn't wait for other people to make special things happen. You have to create your own memories."
In other news, read about Klum's recent holiday party with Ann Taylor.