Fear is based on an illusion - if you fight it, you feed it. Don't feed the illusion. Stop for a moment and realize that all the worries you had in the past didn't prevent you from getting where you are today. Generally people fear two things; that they will lose what they have, or they won't get what they want. When you begin to believe that you can't lose anything, and you can have whatever you want -- you will realize that there is nothing to fear.
Creative Credit to @HipstersLenz