Protein is essential to make and repair our body cells. Protein cannot be stored in the body in the form of protein so it should be taken every day. Muscles need protein every day especially if you are involved in some heavy or hard work like running or exercising. The right amount of protein taken in the daily diet can help build strong muscles. Chicken, meat, seafood, milk, eggs, cheese, nuts, dried beans and peas are some of the good natural sources of protein.