Thinking on work/life balance is also something I've been doing. As a scientist and a writer, I've chosen two pursuits that really have no down time. I write even if I'm not paid, and I engage in science likewise. Employment harnesses my skills in a direction beneficial to others. And in return, I get not only a paycheck, but a focus I usually hadn't considered-- a double win. So I've always enjoyed working, and the prospect of working.
To that, add in that I have 2 elementary school-aged kids. Children drastically change your perception of work/life balance. Once they started school, I worked during the academic year but was home when they got off the school bus, and was home for most of each summer with them.
The downside is I've been limited to jobs that are 'daddy track', which in the sciences are very few and tend to be 'soft money', i.e. 1-3 year terms. Primarily that's due to my stated need for at least 6 weeks unpaid leave each summer.
And as it happens, my latest 3-year contract just ended this summer, so I'm yet again deciding what to do come Fall-- grant work, freelancing, webwork, other?
Asking the work/life balance question of yourself is a very positive thing. It may be unsolveable in an absolute sense, but being able to assess where you are, then go where you want to be, is a useful undertaking.
And to that, I'd add that spending time away from your kids in order to work at a career is not a negative thing. Working hard is a great example for kids. It's important they see the value of work and being integrated with society. We parents are not just their guardians and playthings, but their role models. Working is one of the many roles we play.
Alex, the Daytime Astronomer
The Daytime Astronomer, Tues&Fri here, via RSS feed, and twitter @skyday