Over-Generalizing
Another thing that might cause you not to accept yourself is over-generalizing about something you've done that you don't like. So, for example, if you fail a test you might generalize and say, "I'm really a stupid person." When you do this you are making a statement about all of you all of the time and not just about this one situation at this time. Instead, you might decide that your grade on this test in this subject at this time was indeed poor, and then go on to decide what you want to do about your poor grade, if anything. Getting stuck in over-generalizing discourages you from taking steps that might allow you to do better on the next exam and builds an expectation of future failure.