Regardless of how much time you you spend at work I think having a couple of weeks in a year for yourself to explore the world or be it just mindlessly staring at the sea waves is a reality check and time when you can evaluate whatever you are doing. It is also a good benchmark - if your current job doesn't allow you to do that then - is this a good job? Or you can't really afford to go at the other side of the world, then - am I being paid right? Go figure...
Vacations also can bring interest in your work back. I used to do freelancing and take off at least 8 weeks a year. When I worked I was really interested in my work and put a lot of effort in. Now I work in a corporation with only 3 weeks vacation and it's just one big long never-ending drag of the same thing again and again. The quality and creativity has gone down a lot. I just don't care that much anymore.
