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.
The Lord said, 'When you have done all that is commanded you, say: We are useless servants: we have only done what was our duty' (Luke 17:10). Thus the kingdom of heaven is not a reward for works, but a gift of grace prepared by the Master for His faithful servants.
Labor to acquire meekness. Concerning the heavenly virtues, meekness and humility, the Lord Himself teaches us, saying: Learn of Me, for I am meek and humble in heart; and ye shall find rest unto your souls (Matt. 11:29). Learn not from angels, nor from men, but from Me, He says; that is, from the higher wisdom.
The hour of death will come upon us, it will come, and we shall not escape it. May the prince of this world and of the air (cf. John 14:30; Eph. 2:2) find our misdeeds few and petty when he comes, so that he will not have good grounds for convicting us. Otherwise we shall weep in vain. 'For that servant who knew his lord's will and did not do it as a servant, shall be beaten with many stripes' (cf. Luke 12:47).
Whether you pray with brethren or alone, try to pray not simply as a routine, but with conscious awareness of your prayer. Conscious awareness of prayer is concentration accompanied by reverence, compunction and distress of soul as it confesses its sin with inward sorrow.
Therefore with your whole soul you should acknowledge yourself as worthy of enduring more than you already endure; remember the words which Christ the Savior spoke concerning a good deed done to one’s neighbor, words which should apply equally to every offensive word or deed against one’s neighbor. Whatever you have done to your neighbor, He says, you have done to Me.
Join to every breath a sober invocation of the name of Jesus and the thought of death with humility. Both these practices bring great profit to the soul.
Acquire humility, which scorches the demons, obedience, which opens the door for the Son of God to enter a man, faith which saves a man, hope which makes him unashamed; and love which lets not a man fall away from God.
When you pray to God in time of temptation do not say, 'Take this or that away from me', but pray like this: 'O Jesus Christ, sovereign Master, help me and do not let me sin against Thee. . .'
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).
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.
Was there ever anyone of any breeding who dared to speak the name of Holy Mary, and being questioned, did not immediately add, 'the Virgin'? For by such added names the positive proofs of merit are apparent... And to the Holy Mary, Virgin is invariably added, for that Holy Woman remains undefiled.
Continuity of attention produces inner stability; inner stability produces a natural intensification of watchfulness; and this intensification gradually and in due measure gives contemplative insight into spiritual warfare. This in its turn is succeeded by persistence in the Jesus Prayer and by the state that Jesus confers, in which the intellect, free from all images, enjoys complete quietude.
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.