form of Exercise that involves or improves oxygen consumption by the body. Aerobic means "with oxygen", and refers to the use of oxygen in the body's metabolic or energy-generating process. Many types of exercise are aerobic, and by definition are performed at moderate levels of intensity for extended periods of time. http://en.wikipedia.org/wiki/Aerobic_exercise
Running, swimming, etc.
Many people whether it's really the right path to Physical Fitness.