I am not an introvert but I love and respect a great many people who are. I wish more people would understand what it means to be an introvert - maybe you are and you don't even realise. Introversion does not equal shyness.
Some dreams or goals seem much too large to be achievable; it’s in our nature to stop pursuing it after our initial excitement wears off. Even positive change will feel initially frightening, embrace the feeling and don’t give up.