Naturally fatty fish like salmon, mackerel, herring, lake trout, sardines, and albacore tuna are good sources of omega-3 fatty acids. These are "good" fats that help keep your heart healthy. They may also help keep your brain sharp, especially as you get older. The American Heart Association suggests eating two servings of fatty fish a week. A serving is 3 ounces -- about the size of a deck of cards. Try it baked, grilled, or poached.