Hi, I came across this exercise the other day:
For example, to get rid of the habit of reading slowly, spend a couple of 5-10 minute sessions daily reading as slowly as you can. It's important that you don't allow yourself to start speeding up. As you read at this pace you tell yourself that you are doing this to get rid of the habit, and visualise yourself reading faster. You'll find that after the exercise you will automatically be reading quicker.
I can't remember the whole explanation about the principles of it, but it's something to do with making the habit seem so annoying that you will overcome it. Also, by reading so slowly, your mind knows that you can definitely read faster. It makes progress seem not just possible but probable.
The book said that this method can be used to eliminate most unwanted habits (not smoking or other addictions though - this is pretty obvious anyway, if you've read through the exercise).
Hope this will be of some use to somebody 