Newlywed Carrie Underwood has always been beautiful, but recently, her style changed from ho-hum to red-hot. It's easy to see why she now prefers minis to jeans — her legs look incredible! Fitness specialist Tony Greco (grecoleanandfit.com), who trains the American Idol champ when she's in Ottawa, Canada (where her hubby, Mike Fisher, plays hockey), tells In Touch the secret to Carrie's toned legs is a varied workout. "She trains like a pro athlete," reveals Tony, adding that during her 45-minute sessions, the singer does walking lunges and jumping squats. As to how she stays on target, he admits, "She's very competitive!"