“I’m so nervous!” Kelly Osbourne told InStyle.com backstage before she hit the runway for The Heart Truth’s Red Collection 11th Anniversary Fashion Show, sponsored by the National Heart, Lung, and Blood Institute, Diet Coke, and WebMD. The butterflies-in-the-stomach feeling was one that radiated through backstage at the Hammerstein Ballroom in New York, where 17 stars prepared to walk the runway for a cause—raising awareness for women’s heart health—and InStyle.com had an all-access pass to see every mani, makeup, and hair strand get perfectly in place. “It’s so out of my comfort zone,” fitness guru Jillian Michaels said as she primped for the show. “But this is such a cool event, I’m so excited. Not only about awareness, it’s also just fun!” Click through the gallery to all of the candid behind-the-scenes moments.