The term aerobic means "with oxygen." During an aerobic activity , the cardiovascular system, which includes the heart, lungs and blood vessels, responds to physical activity by increasing the oxygen that is available to the body's working muscles. Aerobic activity involves an exercise routine that uses large muscle groups, is maintained for a long periods and is rhythmic in nature. Regular aerobic activity improves your fitness as your heart becomes stronger and begins to work better. The result is that the heart can pump more blood (thus increasing oxygen delivery to the tissues) with each heartbeat. As your aerobic fitness increases, you can work out longer with greater intensity and recover quicker at the end of the session. Aerobic activity is often coined either High Impact or Low Impact. High-impact aerobic activity includes actions that take both feet off the floor, thus causing more jarring of the joints when the body weight hits the floor again. An example of Low Impact is walking while High Impact is jogging or jumping up and down.
It is important to start at a low intensity and increase this over the following few weeks as the exercise feels easier. For example, 20 minutes of walking, jogging or a combination of walking/jogging may be sufficient to leave you rather breathless and fairly tired at the start of your program, but as the weeks go by, you may need to increase the pace or introduce jogging up some shallow hills to achieve a further increase in fitness. Remind that the heart works better when it is strong. Because the heart is a muscle, it can be made stronger with regular physical activity or aerobic activity. Explain that there are two types of exercise: aerobic and anaerobic. Aerobic activities use the arm and leg muscles and give the heart (and lungs) a continuous workout. Anaerobic activities build and tone muscles but are not as beneficial to the heart and lungs as aerobic activities.
Some of the best forms of aerobic activity are the traditional sports. If you get together and play basketball twice a week with friends, this alone might be enough to keep you fit and healthy. The important thing is to get some kind of aerobic activity, and to make it something that you enjoy enough to keep with it. Some people should consult their doctor before they start a vigorous aerobic activity program. The best advice I have is to join a gym for a month. This will let you try out lots of different aerobic exercises and find out which ones you like.