Too proud to come in last?

I have been working towards the goal of doing a duathon.  Running longer distances.  Bike riding.  But all a sudden I AM scared.  Afraid that I'll be a loser.. That I can't attain.  My heart tells me to run for those that can't.  In faith I'm still moving forward.  I bought a helmet and borrowed a bike, but I just can't get myself to officially sign up.