One thing that's kind of hard about working from home is that you're never really at work and you're never really at home. I can go downstairs to my "office" but I'm still home. At the same time I can be hanging out with my family or watching a movie with them but work is only a flight of stairs away. I find myself getting distracted and feeling like I should really be working and visa versa.
When I worked a real job I tended to not work from home very often most of the time. There would be periods of time where I would have something I needed to work on from home but in general most of the time I spent working was in the office. While I still had trouble leaving the stresses of work behind when I was at home it was much easier to differentiate that time as not work time.
If I tried to keep set hours that might help somewhat but I'm not really a set hours sort of person. This morning I slept in and didn't get started until late morning (10 or 11-ish) and in the past I've tended to wake up before my family and head downstairs to work until they're up. Weekends are just times when I tend to work less but I still typically put some time in (sometimes a lot of time in). I don't even really keep a mental summary of how many hours I've been working anymore.
In this case I have work I need to get done but it'd sure be nice to go sit and read stories with my wife and son (I can hear them reading Goodnight Moon) and then head to bed. The work isn't going to do itself though.