Is this an issue of executive dysfunction? Putting the cart back is such a trivial task that I have a hard time attributing it to laziness. It doesn't sound like you're doing it on purpose to be a dick either. Do you find that you sometimes can't do other things that should also be trivially simple? Like getting up off the couch to grab something two feet away, or deciding that lunch is too complicated because you need to put it in the microwave? My partner and I have both gone through this for most of our lives and it really sucks, but it doesn't have to be that way.