He said, “And now, between 10 and 10:15 you can say the prayer. First, before 10, pray for your children and say “through the intercessions” and then you can begin: “Lord, Jesus Christ, have mercy on me”, mentally. And if different thoughts come to you, say the prayer louder so that you can hear it better: “Lord Jesus Christ, have mercy on me” and you will see that the enemy will leave. You should do like a choir does, for when it sings and we hear spurious noise, we sing louder and we can hear it better. Do not push away the enemy, do not repulse him but gather your thoughts together and intensify your mental prayer and he will leave on his own. Oh, what shall I do with you, what shall I do with you, I love you very much.”
From the book ” Miraculous Occurences and Counsels of Elder Porphyrios“