"When you are terrified by the Law, therefore, say: 'Lady Law, you are not the only thing, and you are not everything! Besides you, there is something greater and better, namely grace, faith, blessing. These do not accuse me; they do not terrify and condemn me. But they comfort me, command me to have hope, and promise me victory and salvation in Christ. Therefore, there is no reason to despair." -- Martin Luther (AE 26, pg. 342)
Here is one of the best baptismal hymns of all time, "God's Own Child, I Gladly Say It." It was written in the 18th century by Erdmann Neumeister. Memorize it and sing it whenever Lady Law won't let you sleep for her continual tormenting of "that powerful jackass," your flesh. (The best place to memorize hymns? In the shower. I'm serious. Get a plastic sleeve and stick it to the shower wall, and insert a copy of a new hymn every week or so. It's edifying and a great way to start the day in prayer).