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.
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.
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 the world belong our desires and impulses. enumerates them: Weakness for wealth and for collecting and owning things of different kinds; the urge for physical (sensuous) enjoyment; the longing for honor, which is the root of envy; the desire to conquer and be the deciding factor; pride in the glory of power; the urge to adorn oneself and to be liked; the craving for praise; concern and anxiety for physical well-being. All these are of the world; they combine deceitfully to hold us in heavy bonds. If you wish to free yourself, scrutinize yourself with the help of that list and see clearly what you have to struggle against in order to approach God. For friendship with the world is enmity with God, and whosoever therefore will be a friend of the world is the enemy of God (James 4:4).
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.
But a sober and prudent man who desires to be saved, when he sees from what it is that he suffers harm, carefully preserves himself from evil remembrances, is not drawn into passionate thoughts, avoids meetings and conversations with those for whom he feels attraction and avoids every occasion for sin, fearing lest he himself ignite a fire within himself. This is the warfare which proceeds from one’s own lust, which a man brings on himself
Think also of this: the person who is bound to earthly things may rejoice but may also be upset or disturbed or grieved over earthly things: his mind is exposed to continual changes. But the joy of your master (Matthew 25:21) is enduring, for God is unchangeable. Thus control your tongue at the same time as you discipline your body with fasting and strictness. Talkativeness is a great enemy of prayer. A spate of fluttering words stands in the way of the words of prayer. This is the reason that we shall render account for every careless word we utter (Matthew 12:36). One does not bring the dust of the road into a room that one wishes to keep clean; thus keep your heart free from gossip and chatter about the events of the day that is past.
To the world belong our desires and impulses. enumerates them: Weakness for wealth and for collecting and owning things of different kinds; the urge for physical (sensuous) enjoyment; the longing for honor, which is the root of envy; the desire to conquer and be the deciding factor; pride in the glory of power; the urge to adorn oneself and to be liked; the craving for praise; concern and anxiety for physical well-being. All these are of the world; they combine deceitfully to hold us in heavy bonds. If you wish to free yourself, scrutinize yourself with the help of that list and see clearly what you have to struggle against in order to approach God. For friendship with the world is enmity with God, and whosoever therefore will be a friend of the world is the enemy of God (James 4:4).
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.
The brothers said, 'Why is it that the monks are obliged to go around begging for the food and clothes they need, like those who are in the world, although our Lord promised them, saying, ‘Seek ye first the kingdom of God and its righteousness, and that of which ye have need shall be given to you’ (Matt. 6:23)?' The old man said, 'This saying is a proof of the wisdom and grace of God toward those who are in the world, for in the majority of cases, the righteousness of the children of this world consists of alms and compassion; but the children of light are righteous people and monks who, in their persons, and in their bodies, and in their thoughts, serve our Lord. And God has made the monks to have need of the children of this world because of His love, so that they may care for each other, and may pray for each other; that is to say, the children of the world must care for the monks and the monks must pray in love for them. And as the children of the world make the monks associates with them in the corporeal things of the world, the monks must make the children of the world to be associates with them in the things of heaven, for our Lord spoke to the children of the world, saying, ‘Make ye to yourselves friends of this mammon of iniquity so that when they have become perfect they may receive you into their tabernacles which are forever.’ (Luke 14:9)
Do not judge and do not belittle anyone, because from this the heart grows faint and the mind is blinded, and from this, negligence appears and unfeelingness of heart is born. Keep ceaseless vigil, learning in the law of God, for through this the heart is warmed by heavenly fire, as is said: 'In my meditation a fire was kindled.'
And the old man also said, 'God saith unto thee thus -- if thou lovest Me, O monk, do that which I ask, and do not that which I do not desire. For monks should lead lives wherein they act not in iniquity, and a man should not look upon evil things with his eyes, no hear with his ears things which are alien to the fear of God, nor utter calumnies with his mouth, nor plunder with his hands; but he should give especially to the poor, and he should not be unduly exalted in his mind, and he should not think evil thoughts, neither should he fill his belly. Let him do then all these things with discretion, for by them is a monk known.' The old man also said, 'These things form the life of a monk: good works, and obedience, and training. A man should not lay blame on his neighbor, and he should not utter calumnies, and he should not complain, for it is written, 'The lovers of the Lord hate wickedness.'
Courage does not consist in defeating and oppressing one's neighbor, for this is overbearingness, which oversteps the bounds of courage. Nor again does it consist in fleeing terrified from the trials that come as a result of practicing the virtues; for this is cowardice and falls short of courage. Courage itself consists in persisting in every good work and in overcoming the passions of soul and body. For our struggle is not against flesh and blood, that is, against men, as was the case with the Jews of old, where to conquer other nations was to do the work of God; it is against principalities and powers, that is, against the unseen demons (Ephesians 6:12). He who is victorious conquers spiritually; otherwise he is conquered by the passions. The warfare described in the Old Testament prefigures our spiritual warfare. These two passions of overbearingness and cowardice, though they appear to be opposites, are both caused by weakness. Overbearingness pulls one upwards and is outwardly something startling and frightening, like some powerless bear, while cowardice flees like a chased dog. No one who suffers from either of these two passions puts his trust in the Lord, and therefore he cannot stand firm in battle, whether he is overbearing or cowardly. But the righteous man is as bold as a lion (Proverbs 28:1) in Christ Jesus our Lord, to whom be glory and dominion throughout the ages.
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.