Ascetic practice is a good thing, but only when done with the right goal in mind. We ought to think of it not as the real task, but as a preparation for the real task; not as the fruit, but as the earth that can, with time, labor, and the help of God, bear trees from which the fruit will come–the fruit that is purity of intellect [the innermost depth of the heart] and union with God. To Him be glory throughout the ages. Amen.
~St Peter of Damaskos
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 [thorns and thistles represent conceit and hypocrisy, self-delusion and formality].
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.
~Ignatius Brianchaninov
Prayerful Life 