Emotions fail human beings
Emotions have been a very vital part of human beings, and they have evolved to help human beings survive in this world.
But they are good for survival, but not advanced enough to handle advance civilization, therefore you are provided with conscious and intellect.
Because they dis function, which results in a loop.
Suppose you are about to deliver a speech and you know your topic very well you are an expert and still you are being afraid. Whats the reason?
The reason is that you want to know what will happen, when you will be on stage and because the event hasn’t happened yet, your mind try to fill that information gap with something and most of the time that something turns out to be a negative thought.