I found this book to be very helpful for three of its main elements. The first element is his approach to defining problems and the two basic types of responses available. The second element is his definition of leadership as an activity that seeks to bring about change, which is engaged in through the conferred authority of those being led. Heifetz's exploration of the powers and constraints of these three types of leadership as well as how one can evolve into the other is astute and informative. Understand the values and issues at stake in the situation.
Adaptive change causes distress in the people being led.
Keep the distress in the tolerable range for doing adaptive work. Too little stress does not motivate people, while too much can defeating as well. Keep the focus on the real issue. Ensure the people who need to make the change take the responsibility of doing the work of change themselves. I found Heifetz's ideas immensely helpful for leadership in church settings.