Build up gradually. Start with one meal. The next time, go for a whole day. Then fast for three days. Then a week. 5. Most people can fast one to three days regardless of the busyness of their schedule. 6. You may tell others about your fast but do not boast. 7. The longer the fast, the more gradually it needs to be broken. Do not break a long fast with a heavy meal. 1. If you have never fasted before, try it. You really have nothing to lose and much to gain. 2.