The Eastern Orthodox contemplative tradition of the prayer of the heart, which has been sustained over fifteen hundred years by monks around the Mediterranean as well as in Russia, has a well-developed sense of the importance of this practice. They not only recommend a 'softening' of the heart as I have described, even to the point of weeping and feeling physical warmth in the chest, but also a concentration of our attention in prayer upon the physical and spiritual heart, the center of our being. I will say more about the prayer of the heart later, but for the purpose of this instruction, the following brief description will do for now.
Place your concentration, your awareness, in the center of your chest. This physical center of your body represents the very center of your whole being, the 'place' where you have your deepest encounter with the Spirit, with Christ. Keeping your attention fixed there, feel your breath causing your chest to expand and contract; feel your heart beating. Feel the heart, which has been made 'soft' and vulnerable to God through joy, contrition, or desire. Remain in this place, feeling your breathing, your heartbeat, your openness to the One who is already present in this very place within you. You may, as the tradition suggests, even feel a certain warmth around your heart as you do so.
— Brian C. Taylor in Becoming Christ