Photographed by Brian Bowen Smith, Jason Derulo lounges poolside for the latest cover shoot from Billboard. Talking to the magazine about how he keeps his six-pack, the 25 year-old singer shares that he uses the Insanity workout DVD. Keeping motivation, he tells himself, “I know it’s hard today, but at some point this will be your warm-up.” Another source of motivation is reminding himself, “When you take your shirt off, you kind of want to be shredded.” Read more on Billboard.com.