I used to be messy. Although I think the main reason was I had too much stuff and was too perfectionistic. It took so much time and energy to keep ALL of that in its place that it was easier to just say "fuck it" and let it go to hell.
Over the years though I've learned to downsize my crap. I still have some clutter, because I can't stand the visual look of sparse rooms. But now everything has its place and I'm usually pretty good with returning things to their places.
I think the stuff I have the most problems with is cleaning the dishes (I always rinse but hate actually cleaning them) and cleaning the bathroom. I don't reuse dirty dishes, but the rinsed ones may end up sitting on the counter for a few days.
Straightening and organizing is one thing, cleaning is another.