What’s the best way to keep productivity high?

Geoffrey James (a contributing editor for Inc.com, is an author of the award-winning blog Sales Source)
How many hours per week should you work to maximize your impact? | A Founder’s Notebook

Conventional business wisdom is that there’s a positive correlation between long work hours and employee productivity. Instead, the opposite is true. It’s now known that long work hours reduce creativity by decreasing the amount of waking hours when the mind is at rest.