Heidi Klum: Download U2 Song 'Invisible' to Fight Against AIDS!

Heidi Klum keeps it chic while taking her kids – Leni, 9, Henry, 8, Johan, 7, and Lou, 4 – to a workout session at JAG Gym on Sunday (February 2) in Culver City, Calif. The night before, the 40-year-old Project Runway host was fierce in leather while arriving on a flight at LAX Airport.