It is as necessary for a man to say the Jesus Prayer as it is for a ship in danger to send out steadily the S.O.S. signal: Lord Jesus Christ have mercy on me.
Blessed are those who acquire the habit of this heavenly practice (unceasing prayer in the name of Jesus), for by it they overcome every temptation of the evil demons, as David overcame the proud Goliath. It extinguishes the unruly lusts of the flesh, as the three men extinguished the flames of the furnace. This practice of inner prayer tames passions as Daniel tamed the wild beasts. By it the dew of the Holy Spirit is brought down upon the heart, as Elijah brought down rain on Mount Carmel.
Just as it is impossible to cross the sea without a boat, so it is impossible to repulse the provocation of an evil thought without invoking Jesus Christ.
Watchfulness and the Jesus Prayer, as I have said, mutually reinforce each other, for close attentiveness goes with constant prayer, while prayer goes with close watchfulness and attentiveness of intellect.
Our good Redeemer, by speedily granting what is asked, draws to His love those who are grateful. But He keeps ungrateful souls praying a long time before Him, hungering and thirsting for what they want, since a badly trained dog rushes off as soon as it is given bread and leaves the giver behind.
Thanksgiving and gratitude is a heartfelt joyous recognition of the divine benevolence and mercy toward us, unworthy ones, shown by Him freely and testified by our heart and mouth.
When God is thanked, He gives us still further blessings, while we, by receiving His gifts, love Him all the more and through this love attain that divine wisdom whose beginning is the fear of God (cf. Prov. 1:7).
Those who have truly decided to serve the Lord God should practice the remembrance of God and uninterrupted prayer to Jesus Christ, mentally saying: Lord Jesus Christ, Son of God, have mercy on me, a sinner.
The practice of the prayer of Jesus holy David, or more accurately the Holy Spirit by the mouth of David, offers to all Christians without exception: 'The kings of the earth and all people, princes and all judges of the earth, young men and maidens - let elders with the young praise the name of the Lord, for His name alone is exalted (PS. 148:11-13).' A literal understanding of the states enumerated here would be perfectly permissible, but their essential meaning is spiritual.
Cultivate the Jesus Prayer and a time will come when your heart will leap with joy, just as it does when you are about to see a person who you love very much.
In the grim struggle with the invisible enemies of our salvation, the supreme weapon is the prayer of Jesus. `All the nations' - the vociferous and wily demons are called nations - `surround me,' says David, `and in the name of the Lord I repulsed them. They encircled and surrounded me like bees, and they burnt like fire among thorns; and in the name of the Lord I repulsed them' (Ps. 117:10-12). With the name of Jesus flog the foes, because there is no stronger weapon in heaven or earth.
In every circumstance we must look upwards. Whether someone does good to us or we suffer harm from anyone, we must look upwards and thank God for all that befalls us, always reproaching ourselves and regarding all the good that happens to us as the work of God's merciful providence, and all the bad as the result of our own sins.
To more conveniently become accustomed to remembering God, the fervent Christian has a special means, namely, to repeat ceaselessly a brief prayer of two or three words. Mostly this is 'Lord, have mercy.' or 'Lord Jesus Christ, Son of God, have mercy on me, a sinner.' If you have not yet heard of this, then hear it now, and if you have not done it, then begin from this hour to do it.
Those who have truly decided to serve the Lord God must train themselves in the remembrance of God and in unceasing prayer to Jesus Christ, saying mentally: 'Lord Jesus Christ, Son of God, have mercy on me, a sinner.' Through such activity, and by guarding oneself from distraction, and with the preservation of peace in one's conscience, it is possible to draw near to God and to be united with Him. For, according to the words of St. Isaac the Syrian, 'Except for unceasing prayer we cannot draw near to God.'
'Lord Jesus Christ, Son of God, have mercy on me, a sinner.' Let your attention and instruction be centered on this. Walking, eating, standing in church before the beginning of the service, continue with the prayer; on entering and departing keep this prayer on your lips and within your heart. In such a manner, with the invocation of the Name of God you will find peace, you will attain to purity of spirit and body; and the Holy Spirit, the Origin of all good, will make for Himself a dwelling within you and will guide you in all piety and purity.