Emotion is a psycho-physical momentary state running parallel with the physiological reactions of a person. This means that it is not a mental state: you cannot imagine experiencing pleasure in order to trigger the biochemical reactions of that instant, but you need to really experience it. Therefore, it follows that you cannot express with your own voice an emotion that you are afraid to try for yourself.
The voice must be able to provoke the listener to have the same emotions as the person speaking, while remaining incredibly clear and therefore understandable to everyone. This is a key point of the Inborn Voice method. You cannot convince anyone to be enthusiastic if you do not feel positive emotions first hand, like a singer cannot convince anyone of deep suffering if, in reality, the singer feels a different emotion.
The increased muscle tension caused by fear of feeling emotional inhibits vocal expressiveness. When it comes to the voice, one of the first barriers to be removed is your own shyness, because it inhibits the naturalness of the body. This does not mean changing your personality, but learning that in the reality of everyday life, we choose when to be shy and how much to be shy: no one is shy in every moment of their life, but only during those in which they choose to be.
Shyness is a state of mind, it is not something real. This cannot be overcome until it is talked about or unless continuing to overcome it, but only with willpower.