Sin, to one who loves God, is nothing other than an arrow from the enemy in battle. The true Christian is a warrior fighting his way through the regiments of the unseen enemy to his heavenly homeland.
He who wishes to purify his faults purifies them with tears, and he who wishes to acquire virtues, acquires them with tears; for weeping is the way the Scriptures and our Fathers give us, when they say 'Weep!' Truly, there is no other way than this.
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.
Silence of lips is better and more wonderful than any edifying conversation. Strive to acquire humility and submissiveness. Never insist that anything should be according to your will, for this gives birth to anger. Do not judge or humiliate anyone, for this gives birth to anger. Do not judge or humiliate anyone, for this exhausts the heart and blinds the mind, and thereon leads to negligence and makes the heart unfeeling.
When you intend to do something and see that your thought is perturbed, and if after invoking God's Name it remains perturbed even by a hair's breadth, know from this that the action you mean to commit is from the evil one and refrain from commiting it. For nothing done with perturbation is pleasing to God.
To act 'according to one’s strength' means to use a little less than necessary both of food, and drink, and sleep... As for food, restrain yourself when you wish to eat a little more, and in this way you will always make use of it moderately.
Even a pious person is not immune to spiritual sickness if he does not have a wise guide -- either a living person or a spiritual writer. This sickness is called prelest, or spiritual delusion, imagining oneself to be near to God and to the realm of the divine and supernatural. Even zealous ascetics in monasteries are sometimes subject to this delusion, but of course, laymen who are zealous in external struggles (podvigi) undergo it much more frequently. Surpassing their acquaintances in struggles of prayer and fasting, they imagine that they are seers of divine visions, or at least of dreams inspired by grace. In every event of their lives, they see special intentional directions from God or their guardian angel. And then they start imagining that they are God's elect, and often try to foretell the future. The Holy Fathers armed themselves against nothing so fiercely as against this sickness -- prelest.
Concerning fasting, do not grieve, as I have said to you before: God does not demand of anyone labors beyond his strength. And indeed, what is fasting if not a punishment of the body in order to humble a healthy body and make it infirm for passions, according to the word of the Apostle: 'When I am weak, then am I strong' (II Corinthians 12:10).
My brother, the passions are afflictions; and so the Lord does not excommunicate us because of them, but He says: 'Call upon me in the time of affliction; and I will deliver thee, and thou shalt glorify me'. Therefore, when beset by any kind of passion, there is nothing more useful than to call upon the Name of God. All we can do, weak as we are, is to flee for refuge to the Name of Jesus. For the passions, being demons, retreat if this Name is invoked.
There is no greater love than that a man lays down his life for his neighbor. When you hear someone complaining and you struggle with yourself and do not answer him back with complaints; when you are hurt and bear it patiently, not looking for revenge; then you are laying down your life for your neighbor.
The vain desires of this world separate us from our homeland; love of them and habit clothe our soul as if in a hideous garment. We, traveling on the journey of this life and calling on God to help us, ought to be divesting ourselves of this hideous garment and clothing ourselves in new desires, in a new love of the age to come, and thereby to receive knowledge of how near or how far we are from our heavenly homeland. But it is not possible to do this quickly; rather one must follow the example of sick people, who, wishing the desired (health), do not leave off seeking means to cure themselves.