I have One Extra Thing as a category of its own on my cleaning schedule. Every (almost) day, in every room, I take a lap and straighten it up, and then there's one more thing to do, that will take hardly any time at all but it's still important and will make a difference. Some days I go off the grid and decide that the patio can wait but the cabinet under my bathroom sink cannot, so my One Extra Thing changes, and that's fine. Because One Extra Thing does not make or break the whole process. It's extra. See? Awesome.
What I like about One Extra Thing (enough to capitalize it!) is that it makes me feel like I'm doing well enough to do just a little more than the minimum. Some days, the minimum (or less...) is all that happens, and that's cool, but on the days when there's one more minute to do something? Doing something makes me feel like "Oh yeah, I got this." And then the next day I get into my car and there aren't any Cheerios stuck to the windows. It's the little things, the little Extra things, that are delightful, yes? YES.
One Extra Thing becomes a habit. If you do it enough, you don't even have to think about it. It just happens, in unexpected ways (not just in housecleaning, because there's more to life than a shiny toilet). It means that on a nice day when you find yourself cutting out of work early, you swing by daycare and pick up the kid, and instead of going straight home to start the regular evening routine, your Extra Thing becomes stopping at the park for half an hour and becoming the Best Mom In The World. It means that when you finally make a hair appointment that's months overdue, you say "I'd also like some highlights" because highlights? are totally Extra. And they are worth it.
So what are your Extra Things? Take a minute, think about what you've got going on, and I bet you can come up with some stuff that has been put off, and while it isn't a big deal, it will make a difference in the long term once it's taken care of. These can be fun (like highlights!) or practical (cleaning out the freezer, which takes five minutes, for real, so just do it already OK?), to be performed as a solo or as an ensemble. One Extra Thing really does matter.