As long as you experience a self, you should feel good about yourself. A good feeling about yourself is the best lie detector you can apply to your thoughts. If your thoughts are thinking things about you that make you feel bad about yourself, then those thoughts are simply wrong. They should not be ignored. They should be actively thrown out.
If you want to criticize yourself, you can criticize your behavior. That is not exactly you, and that you can change though compassionate criticism. If your criticism of your behavior digresses into criticism of your self, then you can use your knowledge of your positive self to recognize those destructive thoughts and toss them away. With behavior, if you notice you have behaved in a way that has hurt somebody, you can apologize. Critically observing your behavior while, believing in your positive self prevents you from critically wounding yourself. Making choices with the guidance of your positive self gives you the benefit of your own wisdom.
If you don’t understand that you are fundamentally wonderful, you may not notice that your negative thoughts about yourself are wrong. If that is your condition, listen, those thoughts are wrong. You may owe yourself an apology. You deserve good feelings. You should get to know your positive self.