Prevailing Prayer

Behold, ye fast for strife and debate, and to smite with the fist of wickedness: ye shall not fast as ye do this day, to make your voice to be heard on high. (Isaiah 58:4)

13 And rend your heart, and not your garments, and turn unto the Lord your God: for he is gracious and merciful, slow to anger, and of great kindness, and repenteth him of the evil. 14 Who knoweth if he will return and repent, and leave a blessing behind him; even a meat offering and a drink offering unto the Lord your God? (Joel 2:13-14)

7 And he caused it to be proclaimed and published through Nineveh by the decree of the king and his nobles, saying, Let neither man nor beast, herd nor flock, taste any thing: let them not feed, nor drink water: (Jonah 3:7)

There is a right way to fast. To come to God with a broken heart. Even when your heart does not feel broken, you can come before God and search your heart and confess your sin. Have you been selfish, proud or undisciplined? Confess it to God and ask to be forgiven and changed in Jesus' name. You can go without food in a special time of soul-searching, or go without other things. Perhaps you should continually go without some of the luxuries life offers and give the money to worthy causes instead. These all help you to receive God's instruction and discipline. God will give it because Jesus has made his unlimited credit available to you if you follow him.
The (wicked) king of (wicked) Nineveh knew to proclaim the kind of fast recommended by God in the book of Joel:
8 But let man and beast be covered with sackcloth, and cry mightily unto God: yea, let them turn every one from his evil way, and from the violence that is in their hands. 9 Who can tell if God will turn and repent, and turn away from his fierce anger, that we perish not?
10 And God saw their works, that they turned from their evil way; and God repented of the evil, that he had said that he would do unto them; and he did it not. (Jonah 3:8-10)
God is not controllable, but he is reliable. If you do what he tells you to, he will not fail to do what he has promised, no matter how bad you have been.
I am starting to include regular soul-searching in my morning prayers, from my study of the sanctuary I think it's something you should consider doing too.