While we try to please God on our own terms, God wants us to live for Him. We call it a "fast" when we do without a self-serving behavior for a limited period of time, but what God calls a "fast" is a life dedicated to serving others.
Abou ben Adhem had a dream. He awakened with a start to find an angel in his room, writing in a golden book. He said to the angel, “What writest thou?” and the angel replied, “The names of those who love the Lord.” “And is mine one?” he inquired. “Nay, not