To me witnesses encourage us, cheer us on and most importantly guide those who do not know Jesus to the right path, The Way. As witnesses our heart's desire should be like God's that all should be saved. Although we know by Scripture all will not be saved by their own choice. However, remember that the final judgment is in God's hands. There is an urgency to tell of the grace of God and the sacrifice of His Son. That feeling of urgency is not something one can instill in oneself. It is a loving thing flowing through Christians. We are only a vessel.