On Thursday, Heidi Klum will walk the runway at New York’s Red Dress Fashion Show.

Like her supporting celebrity cast — including Kim Kardashian, Jordin Sparks and Rose McGowan — Klum isn’t promoting a fashion house. Instead the supermodel and Project Runway host, who is also Diet Coke’s heart awareness ambassador, aims to educate people about heart disease. Klum, who recently gave birth to her fourth child, joins forces with Heart Truth, a heart awareness campaign sponsored by the U.S. government.

Heart disease is the leading cause of death for women. Have you had your heart tested?
Of course. I’m one of those people who go to every single doctor’s appointment. I go to every doctor, including the gynecologist and the dentist, every six months. And I strap my kids into their car seats and bring them to the doctor every six months, too.

Can Diet Coke really be good for one’s heart?
One of the factors that cause heart disease is excess weight. If you lower your calorie intake, you lower your risk of heart disease. Diet Coke has zero calories. It’s not a radical solution, but every little thing helps.

Do you ever get lazy and feed your kids hamburgers instead of your mother’s famous Sauerkraut soup?
They love hamburgers! And fries! And chicken nuggets! And they like my Sauerkraut soup, too. They’ll even eat really healthy things. Last night I made chicken and Brussels sprouts for them.

With four children, how much to you really exercise every day?
I don’t necessarily go to the gym, but thanks to the children I burn a lot of calories. I jump with them on our trampoline, I swim with them and I run after them in our yard. If you work in an office, you probably need a gym, but I’m lucky to have a very active lifestyle.

You’ve designed shoes for Birkenstock. Would you say you were successful in changing its image as professors’ shoe of choice?
I don’t think they’ve ever been untrendy. I think they’re really cool. I’m wearing a pair of Birkenstocks right now. They have my husband’s lyrics on them.

You’re a painter and a singer, too. Do you plan to pursue these activities more seriously?
Before I had kids I did a lot of creative things. When I lived in New York I did oil paintings and attended classes every Saturday, but these days I just paint with the kids. If a charity asks me for a painting I’ll make one, but I don’t have time for much else. It’s interesting how the kids show their personalities. They like to paint, but the older ones weren’t at all interested when I signed them up for soccer. They wanted to play the piano instead.

If you’d not been discovered in a competition at age 19, what would you be doing now?
When I won the competition, I had just been offered a job as a designer in Düsseldorf, so that’s probably what I’d be doing now. It can be fascinating to consider how your life might have turned out, like in the movie Sliding Doors, but I’m too busy to look back.

What’s on your personal iPod right now?
I have no idea. I got one a few years ago, but it’s in a drawer. Actually, I have no idea where it is. When you have kids you don’t have time to listen to an iPod. When we sit on a plane, it’s not as if I’d say to the kids, ‘Entertain yourselves; I’m putting on my iPod now.’

February also celebrates the heart in a different way. How do you and Seal keep the flame burning?
My husband and I have fun together and laugh a lot. It’s not very hard at all when you’ve found the right person; the passion is there or it’s not there.