What I find difficult is having an extremely flexible schedule and my job is project-based. I actually like the flexibility but I admit that I'm not good at managing my time. What tends to happen is that I waste time (or do things that aren't necessarily time wasters but they aren't what I'm supposed to do), then I have to kill myself the next day to catch-up or meet a deadline. So I'm either just putzing around or killing myself - no happy medium.
In my case, it's mostly time management that's an issue - my house, car, closets, etc. are pretty good.