According to the Tao Te Ching, Knowing others is wisdom; knowing the self is enlightenment.
Learning to pay attention to life around us can be very difficult. So many things happen around us in a single day. Learning to pay attention to ourselves is that much harder. You have to make a choice to become a watcher of yourself it won't happen without that awareness. You have to develop the witness, the part of you that can step back from life and impartially observe how you react and think and feel. Only then will we truly know who we are.
Who are you today? Why did you do the things you did, make the choices that you made, and feel the things that you felt?