We start with the heart because it is the core not only of our Whole-Body Mystical Awakening practice, but really the core of human beings and the Christian path. Unfortunately, that isn’t functionally always the case when it comes to much of modern, Western Christianity.
Since we are usually so mind-centric, we may need to give extra attention to the heart. That doesn’t mean we abandon our mind, just that we need more work on the other centers.