Love is manifest in self-giving, self-sacrifice, and self-denial. God is commanding us to an absolute unswerving commitment to holiness, because He knows that our happiness and fulfillment depend on it. If we obey completely and totally, all we’ve done is pay the minimum requirement. “We are unworthy servants; we have only done what was our duty” (Lk 17:10).
—from Reasons to Believe: How to Understand, Explain, and Defend the Catholic Faith by Scott Hahn, Ch. 4: Right and Wrong.