It has been well said that prayer is not preparation for the battle - prayer is the battle. And of all the things we can do to enhance the power and focus of prayer, fasting is doubtless the most potent.
This is where the power is at, because fasting puts us in harmony with an All Powerful God who demands humility from those who wish to be close to Him. Fasting humbles the flesh. When it is done for that purpose, it pleases the Spirit of God.
You can go a certain distance in God, and experience many things, without fasting much, but the highest, richest and most powerful blessings always go to those who together with other disciplines, fast much unto God. The most significant Biblical characters, with the possible exception of Abraham, were all men of fasting and prayer. Jesus, the Son of God, was a man of fasting and prayer (Matthew 4:2). So was the apostle Paul (2 Corinthians 11:27). Moses fasted 80 days. Elijah fasted 40 days. The early church fasted before starting any major work. The greatest spiritual leaders of the 20th century who are making an impact are all men of fasting of prayer to my knowledge. Anyone who started a significant spiritual movement in Christianity was, to the best of my knowledge - Luther, Wesley, Finney, Booth were all men of fasting. In our day, Cho, Bonnke, Osborn, Annacondia are all men of much fasting. If done right, fasting counts a lot with God.
Fasting is not magic, nor does it twist the arm of God. God wants to do many amazing things, but He looks for those willing to urgently make the corrections needed to come into line with him. God resists the proud, but gives grace to the humble. Successful fasting is also the fastest way to learn patience. It takes patience and endurance to fast for more than a day. Many of God's tests come quicker to us when we fast, and we have a better opportunity to pass them. If we want to go far with God we would have to face these tests anyway, but much later, and in a more time consuming and difficult way. We need to "bite the bullet" and embrace the correction God wants to apply to our souls.
Fasting gives you God's focus for your life. It is a major key to hearing God's voice (the other is true worship - the two are related). We need focus from God more than anything. The world we live in is working overtime to distract us, to entice us, to win our hearts and minds, our focus, and to determine our vision. Fasting cuts out the world so we can tune into God. If we are obedient to God fasting will make us catalysts for revival and awakening.