The Jesus Prayer is a great prayer to pray for yourself as well as a great form of Christian meditation. Praying it 20 times, 50 times or 100 times without ceasing (Which I like to do) is a great form of contemplative prayer. How do we do this without it becoming vain repetition?
One way in which I pray the Jesus Prayer (Lord Jesus Christ, Son of God, have mercy on me a sinner) is I focus on each individual word (or phrase) in the prayer as I pray it.
I first emphasize the word "Lord" as I pray the complete prayer. I may do this 5 times or more as I begin the prayer. I meditate on the fact that the one I am praying for mercy to is LORD and has always been LORD and always will be. He is Master and Lord of the Universe. He is God the Son.
The Apostle Paul stated in Col 1:14-18
14 In whom we have redemption through his blood, even the forgiveness of sins: 15 Who is the image of the invisible God, the firstborn of every creature: 16 For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him 17 And he is before all things, and by him all things consist.
I next emphasize "Jesus" which reminds me of His humanity. The Lord of Glory took on human flesh. He did not pretend to be a man but is 100% man. The name Jesus means "Yahweh is salvation" The eternal God took on human flesh to be my Savior. I am praying to the one who took on human flesh to purchase my salvation and asking for His mercy. He died in the flesh on a cross for sinners and purchased salvation for all who believe.
And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
I may do this 5 times or more and then I will emphasize the first two words "Lord Jesus" 5 times or more as I pray the entire prayer. The Lord of Creation who took on human flesh and died for sinners is the source of my prayer.
I will then began to emphasize "Christ" in the prayer about 5 or more times. Christ or Messiah means that He is the anointed one who fulfilled the Old Testament prophecies. Jesus is the one whom the prophets prophesied of.
Jesus himself declared,
Luke 24:44 And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me.
I will then emphasize the phrase "Lord Jesus Christ" as I pray the entire prayer 5 or more times. I think on the Lord of Creation who took on human flesh and was crucified for the salvation of sinners is the promised Messiah of the prophets. It is He whom I am asking for mercy.
I next will emphasize the phrase "Son of God" about 5 times or more. He is God in the flesh that I am praying for mercy. The Apostle Paul stated, And declared to be the Son of God with power, according to the spirit of holiness, by the resurrection from the dead: (Rom 1:4) I do not pray to a dead man but one who defeated death and the resurrection declares Jesus to be the Son of God (God in the flesh!).
Next in the prayer I will emphasize the phrase "Lord Jesus Christ, Son of God" 5 or more times meditating on the entire person of Jesus each time as the one I am asking for mercy from.
In the prayer next I will dwell on the phrase "have mercy" about 5 times or more. Mercy means show compassion, or deliver from harm, or danger. These 2 words are the heart of the supplication I am making. I may be asking for mercy on a situation I am dealing with, or a problem or sickness I am facing or a sin I am struggling with. I need His mercy! The 10 lepers remind us of this in Luke 17:13 And they lifted up their voices, and said, Jesus, Master, have mercy on us.
I then place emphasis on the words "Lord Jesus Christ, Son of God, have mercy" 5 or more times, meditating on the entire person of Jesus. Each time I am asking for mercy from and thinking and praying silently for the need I am asking for His help on.
As I continue the prayer, I will next emphasize the two words "on me" about 5 or more times. I am the one in need of mercy. I cannot make it alone but I am solely dependent upon God's mercy in my life.
The Psalmist reminds me The LORD taketh pleasure in them that fear him, in those that hope in his mercy. - Psalm 147:11
I will again emphasize the previous words 5 or more times in the prayer "Lord Jesus Christ, Son of God, have mercy on me" mediating on His mercy as well as praying for his mercy on either one situation or a variety of issues.
The final words I place emphasis on is "a sinner" 5 or more times. I am a sinner by nature. Original sin dwells in me and wages war on my soul. My sin nature is the enemy within me that needs to be crushed. I need the mercy of Jesus because of my sins. I am asking for the forgiveness of sin as well as the help of God to overcome my sins.
I am reminded of the tax collector''s prayer in the Temple.
And the publican, standing afar off, would not lift up so much as his eyes unto heaven, but smote upon his breast, saying, God be merciful to me a sinner. - Luke 18:13
I conclude the prayer by emphasizing all the words "Lord Jesus Christ, Son of God, have mercy on me a sinner" 5 or more times.
I may then say a short prayer for a need I have or praise God for his mercy.
The Church father, John Chrysostom said regarding the Jesus Prayer,
"...constantly call: “Lord, Jesus Christ, Son of God, have mercy upon me!” in order that this remembrance of the Name of our Lord Jesus should incite you to battle with the enemy. By this remembrance, a soul forcing itself to do this practice can discover everything which is within, both good and bad. First, it will see within, in the heart, what is bad, and later — what is good. This remembrance is for rousing the serpent, and the remembrance is for subduing it. This remembrance can reveal the sin living in us, and this remembrance can destroy it. This remembrance can arouse all the enemy hosts in the heart, and little by little this remembrance can conquer and uproot them."