A problem that I continually face is knowing where my "work" ends and my "home" begins. It is an occupational hazard that comes with working at home for the past 8 years or more. Oh sure there is some physical separation between my office, where most work gets done, and the rest of the house. That helps to a degree. What doesn't help is the fact the "office" is accessible from a mobile phone—a phone that I constantly carry.
Now don't get me wrong, it is exceedingly handy to be able to do business from anywhere my mobile phone. My concern is that there is the potential to unduely impede on my "home" life, i.e. when I should be doing stuff that's not work related. It has, on occasion, happened to me.
At the end of the day, it's a choice to use those tools. Nobody "makes" you use those tools at an inappropriate time. It comes down to having the courage within yourself to draw that line and say "no, this isn't work time."