Assuming you believe you exist, do you also believe that you have a stable, ongoing personal identity?
This blog explores identity in all sorts of ways. Perhaps you would like to start at the beginning.
Some aspects of your identity are probably more ephemeral than others. How sure are you that you know yourself? Who is the self you believe yourself to be?
Do you sometimes reflect upon changes in your identity?
How do you respond when your own sense of identity has changed or has been challenged?