The man with fear of God doesn’t disregard the law of fasting. I am going to talk to you about this issue, because the cunning devil, who hates all good goes to each Christian and tying him in an invisible way with idleness and languor makes him disregard the holy fasting that brings so many spiritual benefits and contributes at our salvation. That’s why I beg you not to listen to the enemy of our salvation and not to let yourself be subdued by the passion of gluttony or return to the bad habits from the past.
It humbles the body of a man. It stops the anger of another one. It draws away someone else’s sleep. It engrains in someone the desire to do good deeds. It purifies someone’s mind and frees it of sly thoughts. It silences somebody’s free untamed tongue so that he won’t say useless shameless words. It impedes someone’s sight to see and seek useless and harmful things.
Fasting slowly thins the thick layer of the sin that cover the soul and chases away darkness as the sun chases away mist, purifies our spiritual eyes and reveals to us the Sun of justice, Jesus Christ.
(Saint Simeon The New Theologian, The essence of the fathers’wisdom, Egumenița Publishing, pp. 97-98)