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.
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.
Give thanks to God for all things, because thanksgiving is intercession before God for our weakness. Judge yourself always and in everything as a sinner and as one seduced - and so God will not judge you; be humble in everything and you will receive grace.
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.
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
