The idea of work-life balance is really a myth. Because you're never in that perfect state. It's really more about constantly reconnoitering and reconfiguring your life to make sure the things that are important to you aren't being neglected.
People like the idea that you can come up with a formula - like a number of hours you spend on work and at home. But that doesn't work if your heart and soul aren't where they need to be at the time.
That's why focusing on the process - not assuming you can find a steady state - is so important.
Here's a good article on this. It also explains -funny enough - why this is such a good day of the year to work on this!