My theory on how to maintain work-life balance after YC is that you have to try to create some semblance of it during YC as well, then turn the volume up afterwards. That can also help avoid the post-Demo Day postpartum crash that comes with pulling a 3 month stint of nothing but work.
So for us, that meant taking Saturdays off, like I mentioned in the article. And it's not just about not working, it's about planning out some kind of epic release and fun time, like going to Monterey for a concert or kayaking around the bay. I have to admit that I wasn't as good about that before YC - I would work until some kind of internal safety valve would blow a gasket and I was flirting with the crispy edges of burnout, then I'd crash uselessly until I could be productive again - and now I'm hoping I've learned a life skill that can power steady productivity for much longer than 3 months.