Among the activities listed, mowing the lawn might be considered aerobic exercise.
Aerobic exercise involves activities that increase your heart rate and breathing while using large muscle groups over a sustained period. Mowing the lawn typically involves physical movement and can elevate your heart rate, depending on how vigorously you do it. The other activities listed (surfing the web, taking a catnap, and paying bills) do not involve significant physical activity and therefore would not be classified as aerobic exercise.