If you want to be best you can be, you cannot worry about what other people think.
Most of us have been brought up to be conventional in our thoughts and actions and to not do anything that might hurt the feelings of others or contradict expectations. In order to be this way, we have to constantly hold ourselves back when we have unique thoughts or desires and thus edit the way we live to fit social expectations. Creativity requires exactly the opposite. You have to think unconventionally and have the courage to express your thoughts or actions despite the expectations of others. When we worry too much about meeting the expectations of others, we restrict ourselves from fully being who we are or what we can be, and that means we cannot be the best that we can.