important part of most condition programs, whether athletic or for general Physical fitness, because it increases cardiovascular endurance and lung capacity. An exercise is considered aerobic when the body uses oxygen to produce energy. This happens with low-intensity, longer-duration exercises such as walking, long-distance running, or bicycling. It also includes any other activity that raises the heart rate and sustains it for a time period at a level that challenges the heart and lungs to become stronger.