Move the empty boxes that had accumulated as potential shipping material into either flattened prepped-for-recycle or collected for organized storage or for at least make a path through this place.
For the much more difficult move the boxes full of books out of remote storage into warehouse shelves, and move the newly arrived restock up the hill from the truck into the remote storage (35 pounds a box, times a couple hundred) I dragooned my video-game-playing teenager. Even he found that this was too many stairs with too much weight, and we quit about half way through - but not before everything was safely stowed where it was out of the weather and accessible for future moving.
Now, even though I left almost all the heavy lifting to him, it's time for a round of ibuprofen and a nap. Or something.