Whether it's post-workout or post-day-in-the-sun, your hair can fall victim to sweat . . . in more ways than one. But if you don't have time to lather, rinse, and restyle before you go back into the humidity again, never fear. You absolutely can refresh your hair without shampoo, and it only takes a few minutes. Getting flawless hair like Hilary Duff (pictured) is easy — promise!