I think it is great to have a good work/life balance, but you can do so even if you work more than 35 hours a week. I just read an article at Bloomberg, discussing how distraught many white-collar workers are over in France about the dissipation of the 35-hour work week. Seriously, they worked only 35-hours a week? I cannot understand how they actually finish all of their work projects within a reasonable time. But that is probably the issue right there, productivity in France is not as high and competitive as Sarkozy would like.
I have worked over 40-hours a week ever since my days as an undergraduate student, and I think I am physically and mentally fine. In fact, my husband and I live by the motto, "work hard to play hard." Monday through Friday, we work long hours and get as much as possible finished at work. And during the weekends we play very hard, whether it is jeeping, hiking, the movies, or whatever. It also does not hurt that both my husband and I enjoy what we do for work. Anyway, I could talk about this subject forever. But basically, I think the French will be ok if they have to work more than 35-hours a week.