I have found for thirty years that preaching and teaching about God's demand that we delight in him more than anything else breaks and humbles people, and makes them desperate for true conversion and true Christianity. Oh, how easy it is to think we are what we ought to be when the emotions are made peripheral. Mere thoughts and mere deeds are manageable by the carnal religious mind. But the emotions--they are the weathercock of the heart. Nothing shows the direction of the deep winds of the soul like the demand for radical, sin-destroying, Christ-exalting joy in God.

John Piper, When I Don't Desire God: How to Fight for Joy, p. 31