Say the prayer internally, with the mind, not with the lips, so that there’s no distraction, with your mind going all over the place. We should place Christ gently in our mind, saying ‘Lord Jesus Christ, have mercy upon me’, very gently. Nothing else. Nothing. Don’t think of anything except the words: ‘Lord Jesus Christ, have mercy upon me’.
Saint Porphyrios of Kavsokalyvia
Ο Θεός, ιλάσθητί μοι τώ αμαρτωλώ και ελέησόν με.