One should continually try to deepen his understanding of the meanings of the prayers he recites, since prayer is called the "service of the heart."
One who prays from the depths of his heart, concentrating his thoughts and feelings upon the profound contents of the prayers, will actually feel that he is standing before God. Tehillim 84:6 states, "Praiseworthy is the man for whom You are his strength, in whose heart tracks are lain." Over the years, prayer lays tracks in a person's heart that bring him closer to God.
Each service is different. Almost every service is recited in a different frame of mind. Sometimes we recite our prayers inspired by the exaltedness of man and the Creation, other times we approach God overwhelmed by our insignificance before God's unapproachable greatness. A moving prayer can arouse thoughts of repentance. It can imbue a person with yearnings to bring the divine into his own life.
At the same time, there are times when a person is unable to feel connected to prayer. Perhaps he has had an exhausting day, and when ready to collapse into bed, remembers that he has not yet prayed. One nonetheless should pray, while trying his best at kavana.
The many prayers and intimate feelings that a person has expressed before God throughout the years eventually crystallize and penetrate his heart. He begins to sense that he is in the presence of the Omnipotent Creator, Whose Shechinah is eternally watching over him. At this point one has reached the exalted perception implicit in the verse "I have set the Lord before me always" (Tehillim 16:5).