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.
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).
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.
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.
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
The humility which in due time and by God's grace, after many struggles and tears, is given by heaven to those who seek it is something incompararably stronger and higher than the sense of abasement felt by those who have lapsed from holiness. This higher humility is granted only to those who have attained true perfection and are no longer under the sway of sin.
Do all in your power not to fall, for the strong athlete should not fall. But if you do fall, get up again at once and continue the contest. Even if you fall a thousand times because of the withdrawal of God's grace, rise up again each time, and keep on doing this until the day of your death. For it is written, 'If a righteous man falls down seven times' - that is, repeatedly throughout his life - 'seven times shall he rise again' [Prov. 24:16].
Four monks of Scetis, clothed in skins, came one day to see the great Pambo. Each one revealed the virtue of his neighbor. The first fasted a great deal; the second was poor; the third had acquired great charity; and they said of the fourth that he had lived for twenty-two years in obedience to an old man. Abba Pambo said to them, 'I tell you, the virtue of this last one is the greatest. Each of the others has obtained the virtue he wished to acquire; but the last one, restraining his own will, does the will of another. Now it is of such men that the martyrs are made, if they persevere to the end.'
Watch constantly, learning to understand God's law, for this warms the heart with heavenly fire. Guard your lips from the idle word, or empty talk, lest the heart gets used to evil words.
Suppose you have ordered yourself not to eat fish; you will find that the enemy continually makes you long to eat it. You are filled with an uncontrollable desire for the thing that is forbidden. In this way you can see how Adam's fall typifies what happens to all of us. Because he was told not to eat from a particular tree, he felt irresistibly attracted to the one thing that was forbidden him.
Let us have recourse to humility on all occasions; for the humble lie prone on the ground, and how can a man fall if he lies on the ground? But a man who stands on a height can easily fall.
A great effort and much toil are needed in prayer before we can reach a state in which our mind is no longer troubled, and so attain the inward heaven of the heart where Christ dwells. As St. Paul says, 'Do you not realize that Christ dwells within you, unless you are worthless?' (cf. 2 Cor. 13:5).