Living the emotions
Emotions are a momentary psychophysical state related to someone's physiological reactions. This means that it is not a mental state: one cannot imagine feeling pleasure in order to trigger the biochemical reactions of that moment, but one must really experience it. From this it follows that no one can express with their voice an emotion that they fear to feel first hand.
The voice must be able to evoke in the listener the same emotions as experienced by the speaker, while remaining incredibly clear and therefore understandable to all. This is a fundamental point of the Inborn Voice Method. You can't convince anyone of your enthusiasm if you don't experience positive emotions yourself, just as a singer can't convince anyone of deep suffering if they actually experience different emotions.
The increase in muscle tension caused by the fear of experiencing an emotion inhibits all vocal expression. When it comes to the voice, one of the first barriers to break down is precisely shyness, because it inhibits the spontaneity of the body. This does not mean changing personality, but learning that in everyday life, we are the ones who choose when and how much to be shy: no one is shy in every moment of their life, but only in those in which they choose to be shy.
Shyness is a mental state, it is not something real. It cannot be overcome as long as we talk about it or with continuous incitement, but only with willpower.