What is Anxiety?

In my book, Mac's Guide to Coping with Stress, Anxiety and Fear, I call anxiety fear's "evil twin". Fear and anxiety are emotions and come from our thinking. When we think fearful thoughts we have fear, same with anxiety. The problem is a lot of times the terms get confused. Fear is a natural response to a real threat. Such as being confronted by a thief. The threat is real, and we can see it. On the other hand anxiety is always based on "fear based thinking". For instance you're worried about an upcoming test, or a medical procedure, or some feeling of pending doom down the road. There is no real threat, only something in your mind. A "fantasy", based on negative thinking. How do you know that you won't pass the test? Or that the medical procedure shouldn't go as expected? You don't. If you studied for the test you should pass. If your doctor is competent why wouldn't the procedure go well? You can always check your anxiety by checking your thinking, and then seeing if your thoughts match up with reality.