You have probably heard such words as: oral prayer, mental prayer, prayer of the heart; you may also have heard discussions about each of them separately. What is the cause of this division of prayer into parts? Because it happens that sometimes through our negligence the tongue recites the holy words of prayer, but the mind wanders elsewhere: or the mind understands the words of the prayer, but the heart does not respond to them by feeling. In the first case prayer is only oral, and is not prayer at all, in the second, mental prayer joins the oral, but this prayer is still perfect and incomplete. Complete and real prayer of word and thought is joined by prayer of feeling.
Spiritual or inner prayer comes when he who prays, after gathering his mind within his heart, from there directs his prayer to God in words no longer oral but silent: glorifying Him and giving thanks, confessing his sins with contrition before God, asking from Him the spiritual and physical blessings that he needs. You must pray not only with words but with the mind, and not only with the mind but with the heart, so that the mind understands and sees clearly what is said in words, and the heart feels what the mind is thinking. All these combined together constitute real prayer, and if any of them are absent your prayer is either not perfect, or is not prayer at all.Theophan the Recluse in The Art of Prayer, p. 66-67
The divisions are helpful, as they enable us to be more attentive to our inner dispositions as we pray. Are we speaking empty words? Do we understand what we say? Is our heart aligned with both thoughts and words? Are we humble before God in our inmost being, and does the Spirit intercede with our spirit in identifying and requesting divine help for our deepest needs?
Our goal is to come before God as complete selves, and, as Theophan says, unite body to mind and heart, thus entering “real prayer.”