I have major depressive disorder and have (finally) started therapy recently. My problem is perfectionism, so if my mind says I can't do it perfectly, then I shouldn't do it at all.
Sometimes when someone (Flylady) tells you what to do and when to do it, it's easier to do. I suggest that if 15 minutes of decluttering is too long, try just 5 minutes. I tell myself that anyone can do anything for just 5 minutes! My house is a mess again, and I need to get back in the Flylady groove! You have reminded me.