In my opinion both confidence and lack of confidence are just images they are not real in most cases. So having either is not really the most optimal thing coz they both are temporary in nature. What you really require is clarity. Clarity of thought and a clear state of mind. I was fat once . I weighed 96 kgs . Through the pandemic I lost 19 kgs. In both my conditions I had clarity. I had clarity as to why my weight was so much and as to how will I bring it down and as a result I was never really thinking about what other people were thinking. Similar clarity helps in other life situations, in relationships, in career prospects. But it is not a cakewalk. You gotta talk.. not to anyone else but sit and talk with yourself , see yourself, accept whatever you observe as is and not judge and then decide the course of action which suits you best!