From my own experience I find that this possibly comes from the knowledge that you set your own hours and aren't trapped. I work all the time, but I've noticed a few times that when I am stuck working (say I have to stay until 9pm and know it rather than I choose to stay until 9pm) the experience becomes different for me at least. It's the feeling that I control all that work that seems to help in the "work all the time and love it" appeal for me.
Another example. I normally always drive to work. But just the thought that I don't have my car and therefore can't leave until the car is returned makes the experience different for me.
This applies to many things. We write on HN not because we are told do. But because we decide we want to. I don't know that I'd like someone telling me to sit up late at night with the laptop and write comments on HN.
OT: Love the shows. Regular listener here.
Thanks. Sorry we have fallen behind lately. A whole myriad of reasons. I hope we get back on track soon!