Like sacrifices, prayer is intended to change man, not God. Its purpose is to cultivate a contrite heart, to promote feelings of humility and inadequacy in man, whilst encouraging reliance on Divine assistance.
Realise that man is comparable to the brute creation except when uplifted by the loving Covenant initiated with our Patriarchs.
Our Sages refer to Prayer as Service of the Heart. But the heart cannot work properly unless the brain functions to stimulate and control its operation. In the physiology of Prayer, too, the mind plays as vital a role as the heart.