We all have seen this quote.If you didn't then my question is how?
Why Be yourself? Why can't I be Batman or Deadpool? Why do I have to be myself in order to succeed? Well my friend let me tell you even though I am 0% successful.
If you are not being yourself you're setting yourself for failure. Let's say you want to be Batman. If you try to be Batman you'll never be as good as batman can be Batman. So you'll fail. But If you be yourself and do what you are passionate and very best at you'll definitely succeed cause no one can be like you as much as you can be like you.
Hope You understand and Be Yourself.