Interpreted more broadly, this result suggests that we invest more effort in exercise when we enjoy it. For the beginner, investing more effort means not quitting. But for the competitive runner, it means pushing just a little harder in key workouts. Itâ€™s a much subtler difference than the difference between maintaining a new exercise habit and returning to the couch, but that extra 1 or 2 percent effort that the runner who is having fun in training gives in tougher training sessions may easily add up to measurable differences in races. Exercise psychology has also shown that aerobic fitness is related to enjoyment of aerobic exercise. Fitter individuals enjoy exercise more than less fit persons because the balance of positive and negative affect (pleasure and pain) during exercise appears to be determined primarily by a personâ€™s proximity to exhaustion, and less fit individuals are closer to exhaustion earlier in exercise and at lower intensities. Put another way, exercise enjoyment is essentially the feeling of exercise capacity, so that the more this capacity grows (i.e., the fitter a person gets), the greater the enjoyment of exercise becomes. In a fundamental sense, the worldâ€™s greatest runners are able to enjoy running more than the rest of us can.