Fasting is an exercise in self-control. Refraining from food, drink and intercourse are difficult because these are among the strongest three desires that humans have. By learning to go without these three human needs for a period of time, Muslims learn self-control so that they can apply this to other aspects of their life. For example, a person who went sixteen hours without water can more easily resist the temptation to drink alcohol or do some other forbidden act. This instills the quality of being conscious of God, which is ultimately the purpose of fasting.