But it's different with pastors-not totally different, but different. The heart is the instrument of our vocation. Charles Spurgeon said, "Ours is more than mental work-it is heart work, the labor of our inmost soul." When a pastor's heart is breaking, therefore, he must labor with a broken instrument. Preaching is the pastor's main work, and preaching is heart work, not just mental work.
— John Piper