The arbitrariness of the 40-hr week has already been extensively discussed. Its antipathy to human happiness has been implied as well. I can only add this reminder, that capitalists have increasingly benefitted from the intense labor of their employees, as seen by the divergence of productivity from pay in the last 40 years -- since 1979, worker productivity (dollars produced per employee) has risen about 80% while hourly pay has risen about 20%. And I understand that this article is not trying to convince people to work 40 hours per week. But the call to "man up" (or "woman up") is a bit misplaced given the context. ;)

“I do not understand one thing in this world. Not one.” — Marilynne Robinson, ‘Gilead’