Saint Nectarios on Fasting

Saint Nectarios of Aegina (1920)

Fasting is an ordinance of the church, obliging the Christian to observe it on specific days. ...He who fasts for the uplifting of his mind and heart towards God shall be rewarded by God, Who is a most liberal bestower of divine gifts, for his devotion. 
...unless one lifts his mind and heart towards God through Christian--not Pharisaic--fasting and through prayer, he cannot attain a consciousness of his sinful state and earnestly seek the forgiveness of sins.. Prayer and fasting--Christian fasting-- serve as means of self-study, of discernment of our true moral state, of an accurate estimation of our sins and of a knowledge of their true character.
The purpose of fasting is chiefly spiritual: to provide an opportunity and preparation for spiritual works of prayer and meditation on the Divine through the complete abstinence from food, or the eating of uncooked food or frugal fare. 
However, fasting is no less valuable for physical health, since self-control and simplicity of life are necessary conditions of health and longevity, as dietetics tells us.
Vol 7 of Modern Orthodox Saints, 2nd ed., p 178