I think I'm rather envious of you - you're so focused on something that you really love, that you forget to sleep or do anything else...

I do have that kind of moment but I also seem to give up well when I know things are physically impossible. I think I balance my time out of necessity - I'm not getting any younger, my brain starts to lose focus in the evening. "If I don't go to bed now, I'll be exhausted tomorrow."