There have been times in my life that I worked a lot more than a 40 hour work week. At those times in life, I was in the middle of a new position and didn't have a whole lot that I wanted to do outside of work. As I enjoyed what I did, I didn't mind putting in the extra time.
But. . . times change, and for the last couple years, I've been more balanced in life. I've spent a lot more time with people and in volunteering in various activities. This article "Margin or Life Balance - Or what $3 gets you" is great at showing that a balanced life that isn't just caught up in work is really worth it.