If you hate your personality, maybe you need to concentrate on other things, for example if you're shy, the problem is solved (maybe for short intervals) if you concentrate on the subject at task and stop concentrating on your fears. Being angry and hating yourself are two different things though, angry could mean your fed up with an attitude of yours, but hating involves sending ill intentions towards yourself, hate will not let you advance, hate will boicot your intentions in doing something for yourself. You have to accept who you are, which isn't equal to confomism. Knowing that all the things you have thought and done is what shaped your personality, will make you understand that you can change yourself. Try to read things you posted on forums several years ago, it may give you insight that there actually have been changes in your personality and it will give you more hopes in changing from now on.

If you can't change you have to realize that you don't want to change, the question is why. Look into things that happened to you, the things that you thought.