Great thread - I really struggle with all this as well. Totally agree with OP that it's a state of mind. When I lived in rented accomodation I always thought I would take care of it better when it was actually "my" house - eventually came to realise it was just me!
Systems are important, but the most vital thing is to just do it - like Janni's picked up on - not to procrastinate. DH and I are awful at collapsing in front of a DVD after dinner without tidying away etc.
I've dabbled in Flylady over the years, and the thing that has most stuck with me is using a timer. It's been mentioned already on here, but it is the one thing that has worked brilliantly for me - so if I have a free hour or two I'll do 15mins cleaning/tidying, 15mins decluttering/sorting, 15mins on admin and 15mins on MN or reading etc. Not that timing MN always works, but it does more often than not.
Lastly, I just have to suck it up re: DH - we've had furious rows over housework, but it works much better if I'm not a martyr about it. I think being a SAHM now also helps, but even in the evenings (when I'm like ok, you've finished your work, when do I get to stop doing mine? etc) I just have to not mind when DH is on the comp. or whatever, and know that a tidy house makes my life about 100000% easier, even if I do it. Plus, it does normally work that if DH sees how much I do he helps as well, and will be more ameniable when I ask him to do something.
PS - I did toy with the idea of getting a cleaner, but thought that as a SAHM in a tiny 2 bed flat it would be just too shameful not to be able to manage it myself. What do you think?
Sorry - v long and rambling!