Fear: a distressing emotion aroused by impending danger, evil, pain, etc., whether the threat is real or imagined; the feeling or condition of being afraid. Dictionary.com
Fear is a vital and important emotion, to alert us of danger and threat to our lives. Unfortunately, some fears are also learned and some are imagined. Past experiences, negative associations, and anticipated threats can all cause fear. That fear can stop us in our tracks. It can cause us not to move forward, or even to revert.
The key is deciphering what is a true threat and what is only a potential threat or a non-threat. In many cases we have the choice to take action, and to step up and do something that might seem scary. The awesome thing about this is, the more you look your fears and the face and take action on them, the less power they have over your future emotions and actions.
Sometimes fear causes us to believe we can't do something. All too often we look at the big picture of something we would like to accomplish or achieve, and we fear that it will be do difficult, too much work, or even impossible. When all we really need to do is break it down into several tiny steps, and just take one step to get started. Getting started can sometimes be the hardest part. One step leads to two, and snowballs us into successful action.
Eleanor Roosevelt said it best. "You gain strength, courage, and confidence by every experience in which you really stop to look fear in the face. You are able to say to yourself, I have lived through this horror. I can take the next thing that comes along. You must do the thing you think you cannot do."