The Jesus Prayer

Saint Paul said, "I would rather say five words in understanding than ten thousand words in tongues."

Even in Greek it reads awkwardly. It would have rhyme and flow if it said, "I would rather say ten words - than ten thousand." etc. But the people knew which five words he meant. Transliterating from the Greek those five words would be Kurie Yesu Christos, Eleason Mae. (Lord Jesus Christ, Have Mercy on me.)  Later it was expanded to say, "Lord Jesus Christ, Son of God, Have Mercy on me, a sinner."

The protestants call this the "salvation prayer" and some think this prayer once said is sufficient for a life time. (Assembly of God Folk are not that naive.)
The orthodox christian prays this prayer every time he/she thinks of Jesus, and when they begin any task, like writing this note.  With Saint Paul's challenge to pray unceasingly, the Orthodox tradition offers the Jesus Prayer, which is sometimes called the prayer of the heart (especially when the heart holds the attitude of this prayer even when we are doing worldly things.) It is first and foremost a prayer of the spirit because the prayer addresses Jesus as Lord, Christ and Son of God; and Saint Paul tells us, "no one can say 'Jesus is Lord' except by the Holy Spirit."

The Jesus Prayer, prayed without effort or with much effort until it becomes second nature to our consciousness is the key to healing and wisdom.  - Archpriest Symeon Elias and Archpriest Paul.