Is Fear Our Worst Enemy?

Fear is expressed in ways such as worry, anxiety, dread, terror, and horror. Sometimes fear can be our enemy, and also our greatest motivation. Fear is more than a simply mental state, it effects both physiology of the body and the chemical balance in the brain as well. When we are afraid it generates stress, which makes us to do things in a different way. Some people use it as an energy booster to solve the problem (technically it is called "adrenaline"). For example, when someone is under threaten, the guy under the threaten may react in two different ways: one is scare to pee their pants, and another is to use the fear as an energy to fight against. I would said mostly fear is our worst enemy. Since if you are in a dark room with no windows and no doors, just 4 walls surrounding you, you might gone crazy. Under this circumstances, the fear is our only and worst enemy. We should be using the fear as an energy booster to solve the problem, but the amount of fear we use should be as less as possible.