Exercise for 80 minutes a day and brisk exercise 80 minutes a week. The speed of walking should be at least 80 steps per minute. Do resistance or weight bearing exercises twice in a week. Avoid doing strenuous exercises for the first time in life after the age of 40. According to Ayurveda one should exercise to his or her body type. Diabetics who exercise should not exercise if blood sugar is lower than 90. In conditions of smog avoid walking early in the morning till sunlight appears.