From Luther’s Commentary on the Galatians:
Train your conscience to believe that God approves of you. Fight it out with doubt. Gain assurance through the Word of God. Say: “I am all right with God. I have the Holy Ghost. Christ, in whom I do believe, makes me worthy. I gladly hear, read, sing, and write of Him. I would like nothing better than that Christ’s Gospel be known throughout the world and that many, many be brought to faith in Him.”
It’s the application of discipline, but in a way completely foreign to any disciplinarian.