Julianne Hough is one of the most fit celebrities in Hollywood. The dancer/actress has shown off her skills in Footloose, Dancing with the Stars, and Grease Live. Now, fans want to know what are some essentials she keeps in her gym bag to keep her in shape and looking flawless. Hough opened up to Allure to share her most important accessory, water. "I never leave without my water bottle," Hough says. "My biggest key to everything is hydrate, hydrate, hydrate, water, water, water. Just when you think you've had enough, you need to have more."