Only very simple exercises like short walks may be undertaken during the fast. A warm water or neutral bath may be taken during the period. Cold baths are not advisable. Sun and air baths should be taken daily. Fasting sometimes produces a state of sleeplessness which can be overcome by a warm tub bath, hot water bottles at the feet and by drinking one or two glasses of hot water. The craving for food will, however, gradually decrease as the fast progresses. Seriously sick persons have no desire for food and fasting comes naturally to them. The simplest rule is to stop eating until the appetite returns or until one feels completely well.