Fasting
The voluntary denial of an otherwise normal function for the sake of intense spiritual activity.

The focus of biblical fasting is always on spiritual purposes.  The heart of one who is fasting is to seek God, most often privately and with no motive to gain approval from people.  Fasting provides the opportunity to reveal those things that control us.  It reminds us that we ae sustained by every word of God and it restores balance in a believer’s life regarding priorities and nonessentials.

Fasting must forever center on God.  It must be God-initiated and God-ordained.
~ Richard J. Foster, Celebration of Discipline