Are you familiar with it?
"Lord Jesus Christ, Son of God, have mercy on me a sinner."
"The Orthodox insist that it would be impossible to outgrow this prayer or to need anything not included by its petition." James Payton in Light from the Christian East.
"The Jesus Prayer is a matter of marvelous versality. It is a prayer for beginners, but equally a prayer that leads to the deepest mysteries of the contmplative life." Bishop Kallistos Ware quoted in Light from the Christian East.
I encouraged someone this week to pray this prayer when she had to "click" on the contents of her internalized over-processing to "close" the file in her mind and pray the Jesus Prayer as a matter of quick, substantial refocus on Christ.