Luke 10:20, "Nevertheless, do not rejoice in this [Satan fall like lighting from heaven, given authority to tread on serpents and scorpions, and over all the power of the enemy, and nothing shall hurt you, v. 18-19], but rejoice that your names are written in heaven."
When the disciples returned with joy from being sent out to Jesus’ harvest (Luke 10:2) because the demons were subject to them in his name (Luke 10:17), Jesus replied by showing them the greater reality of the demise of Satan because of their work as laborers in his harvest. Yet, lest they forgot, he reminded them to treasure and rejoice what matters the most, the reality of his gospel.
Don't loose the sight on the beauty and the glory of the gospel and the God of this gospel who places my name in heaven. The proper motivation for mission comes from rejoicing in the wonder of the gospel, God who has saved a wretch sinner that I am through the sacrificial death and the resurrection power of his Son Jesus Christ. The motivation, the drive for mission flows out of love of the God of the gospel.
THE STORY IS TOLD of Dr. Martyn Lloyd-Jones, one of the most influential preachers of the twentieth century. When he was dying of cancer, one of his friends and former associates asked him, in effect, “How are you managing to bear up? You have been accustomed to preaching several times a week. You have begun important Christian enterprises; your influence has extended through tapes and books to Christians on five continents. And now you have been put on the shelf. You are reduced to sitting quietly, sometimes managing a little editing. I am not so much asking therefore how you are coping with the disease itself. Rather, how are you coping with the stress of being out of the swim of things?”
Lloyd-Jones responded in the words of Luke 10: “[D]o not rejoice that the spirits submit to you, but rejoice that your names are written in heaven” (10:20—though of course Lloyd-Jones would have cited the King James Version).
D. A. Carson, For the Love of God : A Daily Companion for Discovering the Riches of God's Word. Volume 1 (Wheaton, Ill.: Crossway Books, 1998).