So you know what’s going on in your own mind, but not in a relatively short radius around your body? I mean, cardboard boxes ain’t that big. The biggest ones are maybe large enough to fit a car. So to answer your question, I suggest that you find the nearest wall, and figure out if it feels like cardboard or not. If you’re still unsure (because sure, wallpaper can be tricky that way), try pushing through the wall. If it rips, it’s probably cardboard.
By the way, for those of you who were wondering: yes, the album was also titled “Living In A Box”.