lol
@Tamerlane well he was using an old say that exist on many cultures as I'm not japanese and exist in my culture I can say for sure is say that way and I had hear it from many people since I was a kid and even now that I am an older person.
eat - or you will die. (and can't work)
sleep - or you can't work
sex - for a bright future and prosperity ( most common people / workers / uneducated see having family as the brightest future you could ever have and you family will go on).
not preaching just giving a different point of view
I did a "lol" because yours is the most educated from a school/sciences/professional point of view not saying is bad or anything I just too it was interesting.