To stand before the face of God, to cleanse your heart and sanctify the space of your life by invoking His name, this is your aim.We don't know how God cleanses our heart by His name, but we believe that He does so in a supernatural way. In saying the Jesus Prayer, it is not so important whether you are a monk or a drunk, but you are to be very steadfast, attentive, humble, mild, and concentrated.The Jesus Prayer is one of the most important weapons we have in our spiritual struggle to join in union with God. It is simple, clear and proven to be most powerful: "Lord Jesus Christ, Son of God, have mercy on me a sinner." The power is in the name of Jesus. With daily practice we can have His name in our mind and on the tip of our tongue at every moment during the day.
Father Artemy says it is feeling that we develop in our heart.
If you make progress in this humble prayer, you will begin to understand that this commandment is very complete. Your heart will be filled with a spiritual warmth that embraces the center of your feelings. You will come to understand what attentive prayer is, and that your heart has been created for ceaseless prayer. Ceaseless prayer is not a perpetual repetition of this or that word or phrase. The Holy Fathers say that it is the feeling of your heart. Just as you view the objects of this world with open eyes, so your heart, warmed by prayer to God, will partake of the spiritual world. This will be due, not to your piety, but to God's grace. Unceasing prayer may have no words, but you will walk and sleep in the presence of God.Here is a link to learn more about the practice of the Jesus Prayer