Fire makes iron impossible to touch, and likewise frequent prayer renders the intellect more forceful in its warfare with the enemy. That is why the demons strive with all their strength to make us slothful in attentiveness to prayer, for they know that prayer is the intellect's invincible weapon against them.
The head of every good striving and the pinnacle of all corrections is to persevere in prayer, by which we may ever obtain, through entreaty of God, all the other virtues as well. By prayer those who are worthy partake of the sanctity of God and spiritual activity and the union of the mind with the Lord in unutterable love. He who constantly forces himself to endure in prayer is roused by spiritual love to Divine fervor and flaming desire towards God, and he receives, according to his measure, the grace of spiritual, sanctifying perfection.
Until we have acquired true prayer, we are like those who introduce children to walking. Make the effort to raise up, or rather, to enclose your mind within the words of your prayer; and if, like a child, it gets tired and falters, raise it up again. The mind, after all, is naturally unstable, but the God Who can do everything can also give it firm endurance. Persevere in this, therefore, and do not grow weary...
Prayer requires the inseparable presence and cooperation of the attention. With attention, prayer becomes the inalienable property of the person praying; in the absence of attention, it is extraneous to the person praying. With attention, it bears abundant fruit; without attention, it produces thorns and thistles. The fruit of prayer consists in illumination of mind and compunction of heart; in the quickening of the soul with the life of the Spirit. Thorns and thistles are a sign of deadness of soul and pharisaical self-esteem which springs from the hardening of a heart which is contented and elated by the quantity of the prayers and the time spent in reciting those prayers.
The evil spirit tries to scatter prayer as if it were a sand heap, tries to turn the words into dry sand, without coherency or moisture - that is to say, without fervor of heart. Thus prayer may become either a house built on sand or a house built on a rock. Those build on sand who pray without faith, absently, coldly: such prayer is scattered of itself, and does not bring any profit to him who prays; those build on a rock who, during the whole time of their prayer, have their eyes fixed upon God, and pray to Him as to a living person, conversing face to face with them.
Prayer is a branch (of a tree) of meekness, and freedom from anger. Prayer is an expression of joy and thankfulness. Prayer is a remedy against sorrow and depression.
Do you wish God to hear your prayer immediately, brother? When you lift your hands up to heaven, pray first of all, with your heart, for your enemies and God will grant you speedily whatever else you request.
We must always pray to the Lord to tell us what to do, and the Lord will not let us go astray. Adam was not wise enough to ask the Lord about the fruit which Eve gave him, and so he lost paradise. David did not ask the Lord whether it would be a good thing if he took Beth-sheba to wife, and so he fell into the sins of murder and adultery. So with all the saints who sinned: they sinned because they had not called upon God to enlighten and help them. St. Seraphim of Sarov said, ‘When I spoke of myself I was often in error.’