The more I understand that I'm free, the more I do out of gratitude what I was supposed to in the first place.
Well said, brother! Now, my elaboration on my fixed assertion that "gratitude is the visible mark of the Christian."
When we really understand God's requirements, what we call "the Law," if we are honest, we have to cry out, "God, I can't do that! I can't stop being self-centered, to put You in first place! I can't love You with all my heart, and soul, and mind! I CAN'T DO THIS!"
He says, "I know. That's why I sent My Son to do it for you. It's all done. You can quit trying so hard."
This is the Gospel, the Good News. If His Holy Spirit has succeeded in getting me to believe it, to say "Cool! Awesome! Yayyy!" then I immediately say, "Thank You! How can I ever thank You? I certainly can't repay You, but is there something I can do?"
He answers, "Well, y'know those Ten Commandments that you can't keep? The ones that Jesus kept for you? Well, they still reflect My will. Work on those, in the strength of My Spirit, acting out the new nature of My Son that I've started growing in you. You can't fail, even if you fall on your face--you will, you know--because the blood of My Son continues to neutralize your guilt."
Fueled by this sense of gratitude, and out from under the pressure of trying to be good enough in my own strength--loved, cuddled, and comforted--I receive new strength to get up and serve the Lord with gladness. The joy of the Lord is my strength, as Nehemiah told his people when the Law made them weep. God's love is so unstinting... everything good that I do, I do from the position of gratitude. Any other motivation only produces dust and ashes.