I am by no means a neat freak, never have been, never will be. I have a pretty high threshold for clutter. I have found, however, that I function at a higher energy level if the clutter is kept to a minimum. I try very hard to put things back only because I know it makes me happier in the end. This summer has been hard because the kids are home from college and their stuff is all around the house. Yes, I should make them take care of their clutter, but they have drastically improved from last year, so I don't pick on them too much. One child graduated from college this spring and will not leave the house when September hits. Boy, is that going to be a mental adjustment for me - it's my sloppiest child.
What I find, ultimately, is that if I'm too busy to clean, I try to keep one room clutter free. When I walk by this room I get renewed. This inspires me to spend 5 minutes or so at a time to remove clutter from somewhere - wash the dishes, throw out unneeded mail, sweep the kitchen, throw all the kids shoes into the mudroom ;). Love the openness when it works out!