Fear is an emotional response to a threat. It is a basic survival mechanism occurring in response to a specific stimulus, such as pain or the threat of danger. Some psychologists such as John B. Watson, Robert Plutchik, and Paul Ekman have suggested that fear is one of a small set of basic or innate emotions. This set also includes such emotions as joy, sadness, and anger. Fear should be distinguished from the related emotional state of anxiety, which typically occurs without any external threat. Additionally, fear is related to the specific behaviors of escape and avoidance, whereas anxiety is the result of threats which are perceived to be uncontrollable or unavoidable. Worth noting is that fear always relates to future events, such as worsening of a situation, or continuation of a situation that is unacceptable. (Excerpt from Wikipedia article on Fear)
The ability to feel fear and keep moving forward distinguishes the living from the merely breathing." Nicholas Lore
What are you afraid of?