It consists of repeating many times this short prayer: “My Lord Jesus Christ, have mercy upon me, a sinner.”
This is all the practice consists of. Although it seems simple, it needs some effort of concentration and a lifting of the heart to God. These prayers are called “arrow-like prayers” by the Church for they are, in a manner of speaking, spiritual arrows that penetrate the thick veil that can exist between man and God, rise to the pinnacle of heaven and enter the sanctuary of the Lord and are most effective.
When you repeat this prayer with concentration, you will experience the following: You will feel that the Lord is opening your eyes while you talk to Him. You will realize your sins and weaknesses, and lay them in His Hands. You will humble your heart as you ask for mercy and the forgiveness of the many sins you commit against the Lord, against others, and against yourself. Your heart rejoices when you feel the consolations of God’s Spirit who comes near you and comforts you. You then feel that the Lord Jesus Christ enters into your feelings and emotions.
You should choose an appropriate time to carry out this exercise. You can, for example, repeat this prayer several tens of times in a few minutes when you lie down for a nap at noon, or when you go to bed at night. On these occasions, you either get ready for prayer or you protect your heart and mind from being immersed in thoughts or images of evil.
You will initially feel somewhat bored and that it is a monotonous routine. This feeling, however, will disappear if you concentrate on what you are saying and if you visualize the Lord Jesus Christ before you. At the beginning, the words will be uttered by your mouth; then your mind will pay attention to them and you will feel that you are engaged in a humble dialogue with the Lord because of your sins. Next, your feelings are stirred and the prayer is entrenched in your heart in joy and the awareness of the presence of the Lord Jesus Christ.
What is joyful is that this “storing up” in your heart will be very important for your daily life. You will discover that this prayer will leap from your heart to your lips unawares and you will find yourself saying: “My Lord Jesus Christ, have mercy upon me…”. This will alert you to the presence of the Lord and to the possibility of repeating it several times. If you are in a sinful situation, you will correct it quickly, and if you are upset for any reason, you will quickly be comforted by the Lord.