A habit/behaviour is a skill by any other name.  Something that has been practiced over and over so many times that it has now become part of your unconscious behaviour.  This is why it is difficult for you to try and consciously change it.  There is always an originating cause for the start of the behaviour or habit, but fortunately we do not have to go looking for it.  A couple of sessions of BWRT is usually all that is required.