The following is from Mother Teresa on prayer:
It is only by mental prayer and spiritual reading that we can cultivate the gift of prayer. Mental prayer is greatly fostered by simplicity--that is, forgetfulness of self by transcendence of the body and of our senses, and by frequent aspirations that feed our prayer. "In mental prayer," says St. John Vianney, "shut your eyes, shut your mouth, and open your heart." In vocal prayer we speak to God; in mental prayer He speaks to us. It is then that God pours Himself into us.
Our prayers should be burning words coming forth from the furnace of hearts filled with love. In your prayers, speak to God with great reverence and confidence. Do not drag behind or run ahead; do not shout or keep silent, but devoutly, with great sweetness, with natural simplicity, without any affectation, offer your praise to God with the whole of your heart and soul.