The body is like a machine that needs to be used often to keep it working. Keeping fit helps the body look and feel good. An active body helps build strong bones and muscles. Without them, the body would be as wobbly as jelly. Strong muscles are less likely to get injured and can work for longer periods of time. The heart is also a muscle. Doing activities that make the body work hard is great for the heart. A healthy, balanced diet keeps the body active. Carbohydrates are necessary for energy, and come from fruits, vegetables, and foods made from grains such as bread, pasta and rice.