The eight hour workday became the norm after the Ford Motor Company found that number resulted in maximum productivity at its factories. But there is a major problem with this: the idea of an eight-hour day with a short lunch break is based on the most effective formula for physical labor, not mental work and certainly not creative mental work. The brain is much more active – and therefore much more likely to drain – than any other muscle or organ in our bodies. Evidence shows that the brain cycles from highest attention to lowest attention approximately every 90 minutes. This suggests that you should hit the reset button about that often.