Matthew17:21 Howbeit, this kind goeth not out but by prayer and fasting.
The disciples of Jesus had tried to cast out a demon but they couldn't, the demon possessed fellow was brought to Jesus and he didn't waste time in casting out that devil. The disciples wondered why they couldn't but Jesus answered them by saying 'this kind goeth not out but by prayer&fasting. There are demons that may not go out until you fast and pray.
Organized fasting enables us to access raw power, it makes us to operate from the third heavens while still on earth. When fasting, the flesh is weak and the spirit-man is active to handle whatever comes its way. Fasting cannot kill you, it makes you to be more sensitive to God's anointing. Real spiritual men do not joke with fasting because it is a price to pay for power.
The first time I embarked on 3 days marathon fasting, I thought I would die but here I am today. The best way to fast effectively is to shut oneself away from distraction of work, family and friends. Spend enough time praying and studying. If you've been praying for 1 hour before, your prayer time should be more than that when you fast.
Do not fast only to solve problems, but do it as an extension of your regular fellowship with God.
Father, I receive grace to fast In Jesus name. Amen