For those who are: Why are you your own worst critic?

Many of us don’t really like ourselves, and are far more critical of ourselves than anyone else is. When we are complimented we go to great lengths to show others why we don’t deserve those compliments. We believe that we are never good enough; that we have to be perfect; and that we have to attain unattainable goals.

Leaving aside brain chemistry, which is often a component in these things, what do you think motivates your self-criticism? Where does it come from? Are you echoing your parents? Is it some kind of defense mechanism? Is it comfortable? What do you think caused you to be so harsh on yourself?