A case that doesn't seem to have been brought up is practising exposition in a verbal context, such as presenting a speech, making a case or forming an argument. I believe a common talking-to-oneself habit is rehearsal of things you'd like to say, or like to have said in the past. Hijacking this habit to rehearse exposition of useful stuff, as opposed to ruminating over inane and useless things, is a modestly successful project of mine.