Hard work is not the opposite of grace, it is the result of experiencing grace.
D. A. Carson explains:
People do not drift toward Holiness.
Apart from grace-driven effort, people do not gravitate toward godliness, prayer, obedience to Scripture, faith, and delight in the Lord.
We drift toward compromise and call it tolerance; we drift toward disobedience and call it freedom; we drift toward superstition and call it faith. We cherish the indiscipline of lost self-control and call it relaxation; we slouch toward prayerlessness and delude ourselves into thinking we have escaped legalism; we slide toward godlessness and convince ourselves we have been liberated.
(For the Love of God, Volume 2, paragraphing mine)