Can you spend a whole day doing nothing? (That is: nothing constructive.) Would you be satisfied/happy with a day during which you only napped, read a book, watched some TV, ate something, etc.?
A day? Sure, no problem.
Firstly, because time you enjoy wasting is not wasted time. Secondly, because it's a mistake to say that 'resting' isn't a 'constructive' use of time - I seldom get enough sleep, and so dedicating some time just to resting is a good thing.
Or must you get something done even on a "day off"? Would you be uncomfortable if you didn't clean the house, get some work done, gotten out and talked to people, etc.?
Having said the above, I would very rarely choose to dedicate a whole day to "doing nothing". I've usually got more that I need to do than I have time to do it, and I
always have more that I would like to do than I have time to do it. So, while I might enjoy a day spent doing nothing, I would usually
prefer to use that time for something else. I certainly wouldn't have two "doing nothing" days in a row!
(Usually, if I have a day off, I'll use it to try to catch up on a few chores. With a couple of days off, I'll try to wipe out that list. With a week off, I'll do the above, but also try to give the appartment a deep clean, restock the freezer with pre-cooked meals, or otherwise do things to try to make the next several weeks easier. With a month off... well, it's been a long time since I had a month off! Generally, I'd set myself some sort of a project, and try to see that through - create a new campaign, or paint the backlog of miniatures, or similar.)