Authenticity means to be yourself. If you try to act like someone or try to be like them the first to do is ending this situation. Because being like others does not makes you happy. It would be just dramatic because you can not be yourself, you can not be unique. If you try to act like someone that would be the greatest injustice to yourself.
Think that, you are in a world that everyone is same. Think that, 7,888 billion people will wake up at the same hour, go to work at the same time, eat your lunch at the same time with 7,888 billion people. The world would be just a ball that the atoms in it would be same as each others. If you try to be like others or act like them you will be a murderer who kills her or his own life with his or her own hands. If you do not want to waste your time with being an another person, try to be yourself.
To sum up “The greatest injustice a person can do to herself or himself is to try to be someone else.” would explain what I mean. And try o be unique not like everybody.