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.
'If our prayer is not in harmony with our deeds, we labor in vain,' Abba Moses often told the young monks. 'How are we to accomplish such harmony?' they asked him one day. 'When we make that which we seek fitting to our prayer,' explained the saint. 'Only then can the soul be reconciled with its Creator and its prayer be acceptable, when it sets aside all of its own evil intentions.'
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.
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.
Those who have sinned must not despair. Let that never be. For we are condemned not for the multitude of evils, but because we do not want to repent...
When we judge our brother, we censure ourselves in a great sin. When therefore, we shield our brother, God will also shield us from great sins. When we uncover our brother, we drive off the grace of God from over us and we are given over to fall into the same things, so that we learn that we are all weak and the grace of God carries us. Whoever guards his tongue, that one guards his soul from great sins and falls.
Our works in this life are the sowing, and the future life is the harvest of what we have sown. Whatever one sows here, that is what he shall reap there. If one hastens to cultivate the field of his heart, to fertilize it and to sow in it the seeds of immortal grain, he can confidently expect to see a corresponding harvest unto eternal rest and delight. He that sows with tears of repentance shall reap with rejoicing and 'shall be filled,' says the Prophet (Psalms 16:16 and 125:6), for sweet rest follows upon the labors of piety. But rest and refreshment are denied to him who has not labored in the work of piety-he that is idle should not eat, it is said (cf. II Thessalonians 3:10).
If a man has some spiritual gift and feels compassion for those who do not have it, he preserves the gift because of his compassion. But a boastful man will lose it through succumbing to the temptations of boastfulness.