3:Daniel 9:3: And I set my face unto the Lord God, to seek by prayer and supplication, with fasting, and sackcloth, and ashes:
4: And I prayed unto the LORD my God, and made my confession, and said, O Lord, the great and dreadful God, keeping the covenant and mercy to them that love him, and to them that keep his commandments;
5: We have sinned, and have committed iniquity, and have done wickedly, and have rebelled, even by departing from thy precepts and from thy judgments:

Fasting was a sacrifice done without food or water.  This is a true fast.  It was not done to bring great fortune, but it was done for the will on God to come to pass and For deliverance for the brethren.  Fasting was done to purify one's own heart, and to bring revival.

Fasting can loose all binds that satan and witchcraft will put on man, even financial binds.  There is a great power in fasting that is unparallel by prayer alone.

Fasting strengthens the inner man, and gives control over the flesh.  It helps us bring our bodies under the control of the Spirit.

Matthew 6:16: Moreover when ye fast, be not, as the hypocrites, of a sad countenance: for they disfigure their faces, that they may appear unto men to fast. Verily I say unto you, They have their reward.
17: But thou, when thou fastest, anoint thine head, and wash thy face;
18: That thou appear not unto men to fast, but unto thy Father which is in secret: and thy Father, which seeth in secret, shall reward thee openly.