Protein's important for normal body function, and most of us get our protein from meat, poultry, and fish. Try to avoid beef that has been given hormones. Organic beef, pork, and chicken are hormone-free.
Fish is another excellent source of protein and some, like salmon, also supply vital omega-3 fatty acids. Some species (such as tuna and swordfish) may have elevated levels of mercury, and should be eaten in moderation.
Surprise! Protein can also be obtained from seeds (flax and pumpkin, especially), seaweeds, and nuts. Peanut and almond butter are both good sources of protein, a bonus if you are trying to reduce your meat intake.