I'd like to point out that I've never been entirely the type to put in insane work hours. To be fair, I've probably always worked more than the average person, but my particular peak efficiency (as I've been able to see while using RescueTime) comes when I work for bursts and then rest.

All of that being said, ever since I've been a founder (and especially during YC), I've noticed my work time shooting off the charts compared to how I used to work for other companies. I know why this is for me: it's simply because I know that every minute I'm not working is a minute that I'm subtracting from the company's success timeline. People talk about compressing your career into the span of 4 years as a founder, and yeah that's really what's going on. The reason is because if you don't work on your startup, there literally is nobody else that will. And for me, it feels like I'm costing myself money when I'm not working, and that takes a while for people like me to figure out how to balance. I have found that it gets easier after you've reached a more stable 1.0 of your product, but it's always a challenge.

I must say, though, that the idea that YC is a cult is pretty ridiculous.