Working to Live or Living to Work

In my quest for self-reliance and a simpler life, I've found a sticky point where work and life intersect. How much is enough? For me, going back to a slower way of life is ideal. But in our society, work has taken over our lives. 100% effort is not enough anymore. We tabulate our sick days and personal days. We accrue overtime hours to save for the vacations we never take.

Earlier this year, I decided to put a cap on the work that I do. I am not decreasing my efforts, but attempting to make both my work time and personal time more productive. If I don't give myself time to relax at night and on the weekends, my work at school will suffer. It becomes a negative cycle in which I am neither happy nor productive. I still have a nagging feeling that I'm slacking off because, unlike other teachers, I do not stay until 5 or 6 pm and I don't come in at 6 am. Sometimes I feel like I am giving less than my best because I am not pushing myself to the breaking point.

How does one reconcile a strong work ethic with the desire to enjoy one's life?