Fast is abstaining from all evil things

“Fasting is not only abstinence from food. It is only one element of fasting. Fasting is abstaining from all evil things… If I steal, I must especially take care not to do so during the Great Lent. If I have another evil habit, either of foul language or of going out to party in places that are not very decent, during Lent I should make every effort not to do so. Lent is about the whole person: from food to evil thoughts, evil feelings and evil desires.”

“The man must always resist evil, but by fasting this struggle must be subdued, that is, even greater… when a person keeps such a fast, it becomes a treasure for him/her.”

“Fast is a good thing that we should do with regard to ourselves, a heavenly treasure. There are earthly treasures that moths eat and rust destroys, which thieves sneak up to, undermine and steal. And there are spiritual treasures, these are good deeds, which neither moth nor rust destroys, which thieves do not steal. This is the feast to which the Church calls us before the Holy Great Lent.”

Metropolitan Onuphry of Kiev
Source: Union of Orthodox Journalists