There is a sin which is always 'unto death' [1 Jn 5:16]; the sin which we have not repented. Even a saint's prayers will not be heard for the unrepented sin. The person who repents correctly does not imagine that his sins are cancelled through his own effort; but knows that through this effort he makes peace with God.
The Holy Fathers recommend 'moderate' fasting; one ought not to allow the body to be weakened too much, for then the soul, too, is harmed. Nor ought one to undertake fasting too suddenly; everything demands practice, and each one should look to his own nature and occupation. To choose among different kinds of food is to be condemned; all food is God-given, but it is advisable to avoid such kinds as add to the body's weight and appetite; strong spices, meat, spirituous drinks and such foods as are solely for the palate's enjoyment. For the rest, one may eat what is cheap and most easily available, they say. But by 'moderate' they mean one meal a day, and that one light enough not to fill the stomach to satiety.
Those who have sinned must not despair. Let that never be. For we are condemned not for the multitude of evils, but because we do not want to repent...
He is not yet a faithful servant who bases himself on bare knowledge alone; a faithful servant is he who professes his faith by obedience to Christ, Who gave the commandments.
But if you are fearful of becoming self-righteous from working for your own salvation, or afraid of being overcome by spiritual pride, examine yourself and observe that the person who is afraid of becoming self-righteous suffers from blindness. For he does not see how self-righteous he is.
He who wants to cross the spiritual sea is long-suffering, humble, vigilant and self-controlled. If he impetuously embarks on it without these four virtues, he agitates his heart, but cannot cross.
The grace of the Spirit is one and unchanging, but energizes in each one of us as He wills. When rain falls upon the earth, it gives life to the quality inherent in each plant: sweetness in the sweet, astringency in the astringent; similarly, when grace falls upon the hearts of the faithful, it gives to each the energies appropriate to the different virtues without itself changing.
You must set about rooting out the very desire to have things pleasant, to get on well, to be contented. You must learn to like sadness, poverty, pain, hardship. You must learn to follow privately the Lord's bidding: not to speak empty words, not to adorn yourself, always to obey authority, not to look at a woman with desire, not to be angry and much else. For all these biddings are given us not in order for us to act as if they did not exist, but for us to follow: otherwise the Lord of mercy would not have burdened us with them. If any man will come after me, let him deny himself, He said (Matthew 16:24), thereby leaving it to each person's own will ... and to each person's endeavor: let him deny himself.
Always keep this in mind: you are not doing anything virtuous by your continence. Or can it be considered a virtuous act when a man who, out of his own carelessness, has been trapped deep down in a mine shaft, takes a pick and shovel and tries to work his way out? Is it not, on the contrary, quite natural for him to make use of the tools given him by a higher authority to make his way up out of the choking air and darkness? ...From this picture you can gain wisdom. The tools are the implements of salvation, the commands of the Gospel and the holy Sacraments of the Church, that were bestowed upon every Christian at holy baptism. Unused, they are of no profit to you. But used in the right manner they will open your way to freedom and light.
When tested by some trial you should try to find out not why or through whom it came, but only how to endure it gratefully, without distress or rancor.