Fasting was of no benefit to that Pharisee in the Gospel, even though he always fasted two days a week, because he had adulterated it with pride and condemnation of his neighbor (Luke 18:11-12). Not that this means fasting is unprofitable. Moses, Elijah & the Lord Himself showed how beneficial it is for those who fast properly in a way pleasing to God.
If we fervently desire holiness, the Holy Spirit at the outset gives the soul a full and conscious taste of God’s sweetness, so that the intellect will know exactly of what the final reward of the spiritual life consists.
We must with unflagging zeal and care give ourselves to the pursuit of virtue, and constantly occupy ourselves in its practice, lest at any time progress may cease, and regress immediately take its place.... To cease to acquire means to lose, for the will which goes no longer forward will not be far from peril of falling back.
Blessed are the pure in heart, for they shall see God. Everything we do, our every objective, must be undertaken for the sake of this purity of heart. This is why we take on loneliness, fasting, vigils, work, nakedness. For this we must practice the reading of the Scripture, together with all the other virtuous activities, and we do so to trap and to hold our hearts free of the harm of every dangerous passion and in order to rise step by step to the high point of love.
Unless the inner man meditates upon the law of God and is nourished thereby, unless he is strengthened by reading and by prayer, he is conquered by the outer man, and he serves his master.
Praise God continually with spiritual hymns and always remain in meditation and in this way you will be able to bear the burden of the temptations that come upon you. A traveler who is carrying a heavy load pauses from time to time and draws in deep breaths; it makes the journey easier and the burden lighter.
No virtue makes flesh-bound man so like a spiritual angel as does self-restraint, for it enables those still living on earth to become, as the Apostle says, 'citizens of heaven' (cf. Phil. 3:20).
If anyone wants to drive out the demons, he must first subdue the passions, for he will banish the demon of the passion which he has mastered. For example, the devil accompanies anger; so it you control your anger, the devil of anger will be banished. And so it is with each of the passions.
Those who meditate unceasingly upon the holy and glorious name [of Jesus] in the depths of their heart can sometimes see the radiance of their own spirit-intelligence. For when the mind is profoundly concentrated on this invocation, we feel experientially how it starts burning off all the layers of dirt that normally suffocates the soul.
Fasting is beneficial when it is undertaken for quelling desire, humbling the soul, transforming hatred, extinguishing anger, erasing remembrance of wrongs, and for the purity of the understanding and the practice of prayer.
When anyone is disturbed or saddened under the pretext of a good and soul-profiting matter, and is angered against his neighbor, it is evident that this is not according to God: for everything that is of God is peaceful and useful and leads a man to humility and to judging himself.
Fasts and vigils, the study of Scripture, renouncing possessions and everything worldly are not in themselves perfection, as we have said; they are its tools. For perfection is not to be found in them; it is acquired through them. It is useless, therefore, to boast of our fasting, vigils, poverty, and reading of Scripture when we have not achieved the love of God and our fellow men. Whoever has achieved love has God within himself and his intellect is always with God.
Do not pray that things may be according to your desires, for they are not always in keeping with the will of God. Better pray as you were taught, saying: ‘Thy will be done’ on me (Matt. vi 10). And ask thus about all things, for He always desires what is good and profitable for your soul, whereas you do not always seek it.
Grace comes immediately to meet some of those who strive, giving them assurance of the earnest of their inheritance, (Eph. 1:14), letting them taste the promised prizes, as if stretching out a loving hand to welcome them and anointing them for further struggles. With others, however, grace waits for the end of the struggle, and prepares for them the crown of patience as well. As one of the God-bearing Fathers says, 'some receive holy rewards before their labors, some during their labors, and some when they depart.'