I think it was Hofstadter (sp?) who pointed out that when we say "I can do anything I want", although we usually mean that our options are almost umlimited, in fact we're highlighting a severe constraint on our options - namely that we can ONLY do those things we want to do - in fact, in any situation, we can only do the ONE think we MOST want to do (consistent with physical laws, etc).

Sure, you can do anything you want to... but you can't control what you want!