It depends on the intent of the question.

If you are talking about having breaks during your working hours, then I find the Pomodoro method a great way to structure my day. I set to between 40 and 50 minutes and then take the break between to walk around for a few minutes, have a coffee or chat to someone.

If you are talking about work flowing over into your home life. In this one I believe we all have to find the right solution for ourselves.

I have a 3 year old, therefore no work is allowed to disrupt the time between getting home and his bedtime. But, I will often work once he is in bed, emails and sometimes returning calls.

On holiday I will work for an hour each day.

But, I also gain flexibility. If I want to take the afternoon off I can, if I want to go to the theme park I can arrange during the week when it is not so busy. If I want to go shopping I do during the week and always avoid shopping at busy weekend.

Learning to know when it is enough is the hardest part of working for yourself.