1 Corinthians 9:24 "Do you not know that in a race all the runners run, but only one gets the prize? Run in such a way as to get the prize."
This doesn't mean you will never falter or make a mistake. At one time or another we can get side tracked from our destination. Galatians 5:7-8 "You were running a good race. Who cut in on you to keep you from obeying the truth? That kind of persuasion does not come from the one who calls you." But we have a forgiving God. Just because you witness to others does not mean you need to be perfect. imperfection can be used!
if you were running a race that had no finish line wouldn't you want someone to tell you? You see they don't have the good news of Christ. Our prize at the end. And i don't know about you, but knowing what's at the end, makes the tough days a little more bearable.
Acts 20:24 "However, i consider my life worth nothing to me; my only aim is to finish the race and complete the task the Lord Jesus has given me- the task of testifying to the good news of God's grace."