There are different types of exercises and you should try to expose your body to them all of them. Exercise increases your heart rate and moves the muscles in your body. Swimming, walking, playing football, or riding a bike are all examples of exercise that does these things.
Looking at fitness and your body closer up, your exercise should include something from each of these four basic fitness areas:
Cardio-respiratory endurance is the same thing as aerobic endurance. It is the ability to exercise your heart and lungs nonstop over certain time periods. When you exercise, your heart beats faster, sending more needed oxygen to your body. If you are not fit, your heart and lungs have to work harder during exercise. Long runs and swims, or even long brisk walks are examples of activities that can help your heart and lungs work better.
Muscular strength is the ability to move a muscle against resistance. To become stronger, you need to push or pull against resistance, such as your own weight (like in push-ups), using free weights (note: talk to an instructor before using weights), or even pushing the vacuum cleaner. Regular exercise keeps all of your muscles strong and makes it easier to do daily physical tasks.
Muscular endurance is the ability of a muscle, or a group of muscles, to keep pushing against resistance for a long period. Push-ups are often used to test endurance of arm and shoulder muscles. Aerobic exercise also helps to improve your muscular endurance. Activities such as running increase your heart rate and make your heart muscle stronger.
Flexibility is the ability to move joints and use muscles as much as they can possibly be used. The sit-and-reach your toes test is a good measure of flexibility of the lower back and backs of the upper legs. When you are flexible, you are able to bend and reach with ease. Being flexible can help prevent injuries like pulled muscles. This is why warming up and stretching are so important. If you force your body to move in a way that you arent used to, you risk tearing muscles, as well as ligaments and tendons (other parts of your musculoskeletal system).