A teacher in one of my workshops said, "When my students and I are in the flow, then I don't feel like I have to work as hard." I heartily agree. When 90 to 100 percent of my students are excitedly engaged in their tasks and asking deep and interesting questions, I experience joy, and joy is a lot less tiring than the frustration that comes with student apathy.
A great listing to share with staff - following the alphabet!
by Dr. Richard D. Jones - good article in PDF that covers a broad spectrum of information relating to student engagement.