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

From Augustine's Confessions, Book 2:

The life which we live in this world has its attractiveness because of a certain measure in its beauty and its harmony with ... objects that are beautiful. Human friendship is also [a source of happiness]. Yet sin is committed for the sake of all these things ... when, in consequence of an immoderate urge towards those things which are at the bottom of the scale of good, we abandon the higher and supreme goods, that is you, Lord God, and your truth and your law (Ps. 118: 142). These inferior goods have their delights, but not comparable to my God, who has made them all.

"Always you renounce a lesser good for a greater; the opposite is what sin is. . . . The struggle to submit . . . is not a struggle to submit but a struggle to accept and with passion. I mean, possibly, with joy. Picture me with my ground teeth stalking joy--fully armed too as it's a highly dangerous quest."

Flannery O'Connor, The Habit of Being