Ezra 8:21 Then I proclaimed a fast there at the river of Ahava, that we might humble ourselves before our God, to seek from Him the right way for us and our little ones and all our possessions.

Those who know their God shall be strong and carry out great exploit. Every great men in scripture were men who are know for fasting, the reason is, there are many things you won't be able to handle without it. When we fast, our spiritual sensitivity and accuracy is high. 

What many people do fasting is abstaining from food, and either sleep or spending time watching movies in order to while away time. But you must know that when you are fasting, it is time to eat spiritual food, which God's word. Recognize that God want to give you fresh manna. Spend time in worship and prayer as well. 

Deuteronomy 8:3 So He humbled you, allowed you to hunger, and fed you with manna which you did not know nor did your fathers know, that He might make you know that man shall not live by bread alone; but man lives by every word that proceeds from the mouth of the Lord.

In order words, our existence is not because we are eating earthly food alone. You cannot live and survive this world eating bread alone, you need to eat something else. God's word is the food of the spirit, you must take time in the word listening and reading the same.