Pope Shenouda III
Drills in certain virtues
It is possible to benefit by profound spiritual feelings that you may experiences while fasting. This may allow a person to gain any virtue that his heart longs for. This may include tolerance, forbearance, calmness, meekness, being cautious, respect for others, generosity, honesty in work, righteousness, discipline, etc.
If you came out of every fast well versed in one virtue, it would be of great spiritual gain for you.