The image of your personality is created by the things you say, do and think about. Change those three things and you change this illusion you call a "personality".
Your identity is not this fixed thing but this everchanging pattern of behavior. Your personality is only what you think of yourself.
You can choose who you are. If your personality is nothing more than an idea you have of yourself. It is ultimately what you decide it to be. You can change your view of yourself and ultimately change what people call your personality.
Changing your perspective of who you are will affect the way you think and behave and essentially create whatever persona you want.
Although you understand that it is not real. You play the game like everyone else. Often you may even forget that it is a game and you start really believing in this character but it is important to remind yourself that it is only an idea and who you truly are is the universe.