Fear is one of the most powerful emotions out there. It is intense and requires a primal response: Fight or Flight. We have a binary choice: Back away or confront the challenge heads on.
Back in the days fear was a lot more valuable. Indeed many of the challenges meant death in case of failure (you better run away from that bear). In today's society failure usually only mean a broken ego and a loss of resources. Failing is recoverable. We should therefore approach our relationship with fear in a different way. We know the costs of failure so we now have to balance them with the rewards of success. Is the fear of failure worth giving up on your dreams without even trying?
My advice is to use fear as a motivational tool, let it light a fire that will make you work in overdrive and give it your all. If despite your efforts you fail, you will have a certain calm. You will be at peace knowing you gave it all you could.