If you have read (or read about) “The Life-Changing Magic of Tidying Up" by Marie Kondo, you will be familiar with one of her most important rules for eventually having less stuff, and being happy about it. That is: you must consider all of your belongings by category, all together at once. That means you gather ALL of your belongings in a given category from everywhere inside (and sometimes outside) your home, and put them in one spot (such as the bedroom or living room floor). Then you hand...