When you pray, keep your memory under closed custody. Do not let it suggest your own fancies to you. After this, the memory has a powerful proclivity for causing detriment to the spirit. The state of prayer can be aptly described as a habitual state of impertable calm. We seek after virtues for the sake of attaining to the inner meaning of created things. That's the real purpose of being a righteous person.
"Do not pray for the fulfillment of your wishes, for they may not accord with the will of God. But pray as you have been taught, saying: Thy will be done in me (cf. Luke 22:42). Always entreat Him in this way - that His will be done. For He desires what is good and profitable for you, whereas you do not always ask for this." - Evagrius Ponticus.
Swami Sarvapriyananda speaks on Evagrius's teachings on prayer.