The most suitable time to exercise is when the sun begins to rise. Because exercising too early can easily cause a stroke, especially in the elderly, and if it is too late, the sunlight will have a bad effect on the skin. Sunrise time will vary according to the seasons, specifically, on summer days you should exercise around 5:30 - 6:00, and on winter days because the weather is quite cold, it is best to exercise around 6:00 to 6:30.