[cenhyperion]

I firmly believe that the reason most major religions standardized a sabbath day was for mental health reasons. There's a lot of value to taking a day for yourself in which you do no work.

Even if you love what you do, you can't do it for 10 hours every single day for years.

[mattgibson]

I've heard something similar suggested as part of the reason for the spread of Islam. 5 prayer-breaks per day where you get to chill out in the shade for a bit is a pretty compelling offer in a hot part of the world. Especially if you are doing manual labour.