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.
If we want to do something but cannot, then before God, Who knows our hearts, it is as if we have done it. This is true whether the intended action is good or bad.
There is a sin which is always 'unto death' [1 Jn 5:16]; the sin which we have not repented. Even a saint's prayers will not be heard for the unrepented sin. The person who repents correctly does not imagine that his sins are cancelled through his own effort; but knows that through this effort he makes peace with God.
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.
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.
A prayer offered while one has any cause to reproach a fellow man is an impure prayer. There is only one whom the praying person may and must reproach, and that is himself. Without self-reproach, your prayer is as worthless as it is while you are reproaching someone else in your heart. Perhaps you ask: How can one learn this? The answer is: One learns it through prayer.
Our Lord and God made flesh has offered us the image of all virtue, as an example to the human race; and to recall us from the ancient fall, has set before us, as in a picture, His all-virtuous life in the flesh. Among many other good examples, He has shown us how, after His baptism, when He went out into the wilderness, it was with fasting that He began His mental wrestling with the devil, who came against Him as an ordinary man. And through this manner of His victory, our Lord has taught us, His unprofitable servants, how we must practice our wrestling against the spirits of evil, that is with humility and fasting and prayer and sobriety: which He observed though He Himself had no need of such things, being God...
The heart which is constantly guarded, and is not allowed to receive the forms, images and fantasies of the dark and evil spirits, is conditioned by nature to give birth from within itself to thoughts filled with light. For just as coal engenders a flame, or a flame lights a candle, so will God, who from our baptism dwells in our heart, kindle our mind to contemplation when He finds it free from the winds of evil and protected by the guarding of the intellect.
But, say the saints, now that you recognize the darkness in your own heart and the weakness of your flesh, you lose all desire to pass judgment on your neighbor. Out of your own darkness you see the heavenly light that shines in all created things reflected the clearer: you cannot detect the sins of others while your own are so great. For it is in your eager striving for perfection that you first perceive your own imperfection. And only when you have seen your imperfection, can you be perfected. Thus perfection proceeds out of weakness.
Cultivate the Jesus Prayer and a time will come when your heart will leap with joy, just as it does when you are about to see a person who you love very much.
When tested by some trial you should try to find out not why or through whom it came, but only how to endure it gratefully, without distress or rancor.
