from Saint Silouan (1866-1938), Orthodox monk
If you want to pray with the mind in the heart and do not manage to do so, say your prayer with your lips and fix your mind on the words of the prayer, as is said in the Ladder of Perfection [of St John Climacus]. With time the Lord will give you undistracted “prayer of the heart” and you will pray with ease. Certain people, during the work of prayer, after forcing their intellect to descend into their heart, have sunk to such an extent that they cannot even articulate the prayer with their lips. But as for you, understand the law of the spiritual life: its gifts are granted only to simple, humble, obedient souls. The Lord will give prayer to anyone who is obedient and restrained in everything—in food, words, movements—and it will be accomplished with ease in his heart.