Nick Carter has gained a cause — and shed 30 pounds! Over the past few months, the singer has been getting in shape for two new gigs. He's promoting the first Backstreet Boys album in two years and he's working with the United Nations after being named a Special Ambassador in May. "People like Bono have inspired me to put my celebrity to use," Nick, 27, says. "It's an actual job. There are commitments that I must keep in order to be the voice of dolphins and conservationist issues."