One of the great mental laws is the Law of Substitution. This means that the only way to get rid of a certain thought is to substitute another one for it. You cannot dismiss a thought directly. You can do so only be substituting another one for it. If I say to you, "Do not do think of the Statue of Liberty," of course, you immediately think of it. If I say, "I am not going to think of the Statue of Liberty," that is thinking about it. But if you become interested in something else, you forget all about the Statue of Liberty -- and this is a case of substitution. When negative thoughts come to you, do not fight them, but think of something positive. Preferably think of God; but if that is difficult at the moment, turn your attention to something quite different.