Country singer Carrie Underwood showed off her bikini body on Instagram, lounging on a sun-bed and enjoying some sunshine. The 40-year-old mother-of-two looked fit in a green bikini by Heidi Klein. Underwood has been sharing photos of herself as she rehearses for her Vegas residency and headlined the Rogue Music Fest over the weekend. She recently shifted her workout goals, focusing on strength and energy rather than a specific size. Underwood believes in taking care of oneself and playing the long game when it comes to fitness.