So many aspects of ministry demand excellence, and there are not enough hours in the day to be excellent in all of them. When I was a young man, I heard D. Martyn Lloyd-Jones comment that he would not go across the street to hear himself preach. Now that I am close to the age he was when I heard him, I am beginning to understand. It is rare for me to finish a sermon without feeling somewhere between slightly discouraged and moderately depressed that I have not preached with more unction, that I have not articulated these glorious truths more powerfully and with greater insight, and so forth. But I cannot allow that to drive me to despair; rather, it must drive me to a greater grasp of the simple and profound truth that we preach and visit and serve under the gospel of grace, and God accepts us because of his Son. I must learn to accept myself not because of my putative successes but because of the merits of God’s Son. The ministry is so open-ended that one never feels that all possible work has been done, or done as well as one might like. There are always more people to visit, more studying to be done, more preparation to do. What Christians must do, what Christian leaders must do, is constantly remember that we serve our God and Maker and Redeemer under the gospel of grace.
-D.A. Carson, Memoirs Of An Ordinary Pastor, p. 92,93
(HT: Biblical Theology)