“Now that you have had the experience of silence and prayer of the mind and have tasted the sweetness that this brings, you must always keep this in your heart— whether you are eating or drinking, having a conversation with someone, traveling, or sitting in your cell— with attentive thought and an undistracted mind, do not stop repeating that prayer, psalmodising, and learning from the prayers and the psalms. Even when attending to your most pressing needs, do not let your mind remain empty, but exert it to study and to pray in secret. In this manner you will understand the profound meaning of Holy Scripture and the power that is hidden there; you will teach your mind to pray unceasingly and will thus fulfill the words of the Apostle that command us to Pray without ceasing [I Thess. 5: 17].
Diligently practice watchfulness over yourself and guard your heart against accepting any evil, vain, or futile thoughts, but let your heart, in secret, alternate learning from the psalms and praying Lord, Jesus Christ, Son of God, have mercy on me! Do this always— when you sleep and when you awaken; when you are eating, drinking, or having a conversation. Then, when you chant the psalms with your mouth, be careful that you do not only mouth the words while your mind wanders elsewhere.” — Abba Philemon
Cleary, Thomas. The Way of a Pilgrim and The Pilgrim Continues His Way (Kindle Locations 3475-3483). Shambhala. Kindle Edition.