CARRIE UNDERWOOD has some of the best legs in country music -- and it's because Carrie works hard to keep them looking so good. She doesn't do all the hard work on her own. According to Glamour, Carrie calls in her favorite trainer, Erin Oprea, to help whip her legs and thighs into shape. The two have been working out together for a long time. Want to get Carrie-like legs? You’ll have to start with everyone’s not-so-favorite workouts -- squats and lunges. Carrie does multiple types of squats and lunges, some with additional weights.