The fight for joy is good because by it God is greatly glorified. When we devote ourselves to resist the idolatrous power of every craving, every desire, every pleasure that is not God, then God is exalted as the superior Treasure of our lives. Fighting against all alien joy shows that we know the infinite worth of God. Therefore the fight for joy is a good fight.

John Piper, When I Don't Desire God: How to Fight for Joy, p. 39