1) Watermelon Juice. Made up of over 90% water, this juice is one of the most hydrating options you can find and contains antioxidants that help decrease chances of heart disease, cancer and high blood pressure. Drink it while working out—the citrulline helps to reduce muscle soreness and lower chances of inflammation (bonus: the amino acid is also a natural libido booster for men). Our pick: WTRMLN WTR