Listen to Dr. Watson. They key to breaking any bad habit is to replace it with something else, not just go use will power. I try and imagine my girlfriend pleasuring me. I get many sensations, like for one I feal like I just ate some junkfood. Its hard to concentrate at first because serotonin is low, which might have provoked the urge in the first place. This postive visualization exercise will boost serotonin and you should be able to concentrate on the image better. The image becomes richer and you become more relaxed. You do this everytime instead of the other thing and it will become easier. Its easier because you have devolped a sense of controll. Soon it will be just as easy doing the postive visualization exercise as it is to do the other thing.
I am reading about self hypnosis which envolves some of things I just mentioned. I just want help myself deal with truama issues in addition.