"It may be, my daughter, that you do not know how to practice mental prayer*, for unfortunately it is a thing much neglected nowadays. I will therefore give you a short and easy method for using it, until such time as you have read sundry books written on the subject, and above all till practice teaches you how to use it more perfectly.
"First, a lively, earnest realization that God’s presence is universal; that is to say, that God is everywhere, and in all, and there is no place, nothing in the world, devoid of God’s Most Holy Presence, so that even as birds on the wing meet in the air continually, we, wherever we go, will meet with that Presence always and everywhere. It is a truth which all are ready to grant, but all are not equally alive to its importance. …
"We do not see our God, and although faith tells us that he is present, not beholding him with our mortal eyes, we are to apt to forget him, and act as though he were afar: for, while knowing perfectly that God is everywhere, if we do not think about it, it is much as though we knew it not. And therefore, before beginning to pray, it is needful always to rouse the soul to a steadfast remembrance and thought of the Presence of God. … Therefore, when you make ready to pray, you must say with your whole heart, 'God is indeed here'."
Introduction to the Devout Life
(* "Mental prayer" is meditation in the Catholic tradition. Meditation refers to deep consideration of scripture or some other holy words.)