It is easier to answer the question "who am I not?" We are not the incessant negative thoughts in our head, we are not the labels we attach to ourselves, and we are not the "pearl" in the oyster. We are, instead, the creator of the "pearl," or the oyster itself.
Let me explain. When an oyster takes in a foreign object, like the proverbial "grain of sand," it begins to coat the grain of sand with a smooth substance (nacre) in order to reduce the irritation the foreign object causes. The foreign irritant covered with layers of nacre becomes a pearl.
In our lives, the foreign implant is the double message that "we are not worthy" and "we are not responsible." We are not born with this message inside us, we acquire this message from the environment and we cover the pain of the message with our own "nacre." Eventually we build a pearl of our own; we call it the ego.
Our ego is not us, but rather it is a creation of the "real" us. The problem is, we pay so much attention to our own ego that we think our ego is us. We forget that we, the authentic us, is the one who created the ego in the first place. It is as if the ego, or pearl, takes on a life of its own. It whines if it doesn't get its own way, it is demanding, it is frail, it attempts to be controlling; after all, it is founded on the principle that we are "unworthy" and "not responsible."
If your ego has hijacked your life, try to remember that you are not your ego. You created your ego and you can re-center yourself in your creative self and get on about the business of living in harmony with a great and vast sea of life.