Don't stop moving. Sure, it's what every gym instructor says, but Cameron Diaz actually lives by those words. As a long-time fan of circuit training, the star has the legs to prove that a routine of short intervals of training on different machines is a method that works. Often spotted leaving her gym sessions, the actress has revealed that sweat and hardwork are essential to maintaining her lean physique. Her trainer Teddy Bass has also shared some of her thigh-trimming workouts to give you a 'leg-up' in achieving a star-worthy body this year.