If thou, 0 man, dost not forgive everyone who has sinned against thee, then do not trouble thyself with fasting. If thou dost not forgive the debt of thy brother, with whom thou art angry for some reason, then thou dost fast in vain. God will not accept thee. Fasting will not help thee, until thou wilt become accomplished in love and in the hope of faith. Whoever fasts and becomes angry, and harbors enmity in his heart, such a one hates God and salvation is far from him. - Venerable Ephraim the Syrian

It is necessary most of all for one who is fasting to curb anger, to accustom himself to meekness and condescension, to have a contrite heart, to repulse impure thoughts and desires, to examine his conscience, and to put his mind to the test. To verify what good has been done in this or any other week, and which deficiency we have corrected in ourselves in the present week. This is true fasting. - Saint John Chrysostom

An excellent faster is one who restrains himself from every impurity, who imposes abstinence on his tongue and restrains it from idle talk, foul language, slander, condemnation, flattery and all manner of evil-speaking, who abstains from anger, rage, malice and vengeance and withdraws from every evil. - Saint Tikon of Zadonsk

Seest thou what fasting does: it heals illnesses, drives out demons, removes wicked thoughts, and makes the heart pure. If someone has even been seized by an impure spirit, let him know that this kind, according to the word of the Lord, “goeth not out but by prayer and fasting” (Matthew 17:21). - Saint Athanasius the Great

By fasting it is possible both to be delivered from future evils and to enjoy the good things to come. We fell into disease through sin; let us receive healing through repentance, which is not fruitful without fasting. - St. Basil the Great

The strictness of the Forty Days puts to death the passions, extinguishes anger and rage, cools and calms every agitation springing up from gluttony. Just as in the summer, when the burning heat of the sun spreads over the earth and the northern wind renders a benefaction to those who are scorched by dispersing the sultriness with a tender coolness: so fasting also provides the same, by driving out of bodies the burning which is the result of overeating. - Saint Asterius of Amasia

As bodily food fattens the body, so fasting strengthens the soul; imparting to it an easy flight, it makes it able to ascend on high, to contemplate lofty things and to put the heavenly higher than the pleasant and pleasurable things of life. - Saint John Chrysostom

Fasts do not shorten a man’s life, for example: Symeon the Stylite lived for 103 years, St. Cyril the Anchorite lived 108 years, St. Alypius the Stylite - 118, Venerable John the Silent - 104, Anthony and Theodosius the Great - 105, and Venerable Paul of Thebes - 113.