The heart is the innermost vital part, or essence of something.
Building on this understanding, the heart of leadership takes on a completely different picture. Consider the growth of the early church. Leadership was the innermost vital part and the essence of its growth.
If we really want the church to grow today, maybe we need to pay attention to the heart of leadership. Perhaps leaders need to take a greater role in fulfilling the God-given task of being the innermost vital part and essence of the church.
When this happens, we will see a revival.