Tim Ferriss has a short 5-minute video from the Google I/O conference. He talks about first defining your fears as a means to overcome them. I agree that our worst fears never come to pass. They sure can hold us hostage and keep us from acting, but I have never been in a situation where they have actually occurred in my own life!
It is a worthwhile exercise to consider the worst-case scenario when confronted with a big decision. Write it down. Look at it. Laugh at the absurdity of the chance of it actually happening. Recognize that even if it did happen, that you would still be OK at some level (you would still have physical health, or emotional health or good friendships or peace of mind ….etc.). Then press on with newfound confidence that the worst isn’t really all that bad.