The harsh winter months can leave you sick, stiff, and lethargic, making your sofa and snuggie seem more attractive than dance class. Happily, Vitamin D is a natural remedy that strengthens your immune system, bones and muscles—and boosts your mood to boot. Known as the “sunshine vitamin” because of the body’s ability to produce it when exposed to the sun, Vitamin D is also found in foods like fatty fish, milk (soymilk too), and oatmeal. If you don’t plan on lounging in the snow to soak up some rays, add these foods to your diet (or take a supplement) and you’ll combat the winter blues and that oncoming flu in one fell swoop.