Working in 90-minute intervals turns out to be a prescription for maximizing productivity. Professor K. Anders Ericsson and his colleagues at Florida State University have studied elite performers, including musicians, athletes, actors and chess players. In each of these fields, Dr. Ericsson found that the best performers typically practice in uninterrupted sessions that last no more than 90 minutes. They begin in the morning, take a break between sessions, and rarely work for more than four and a half hours in any given day. ...

Along the way, I learned that it’s not how long, but how well, you renew that matters most in terms of performance. Even renewal requires practice. The more rapidly and deeply I learned to quiet my mind and relax my body, the more restored I felt afterward. For one of the breaks, I ran. This generated mental and emotional renewal, but also turned out to be a time in which some of my best ideas came to me, unbidden. Writing just four and half hours a day, I completed both books in less than six months and spent my afternoons on less demanding work. ...

By managing energy more skillfully, it’s possible to get more done, in less time, more sustainably. In a decade, no one has ever chosen to leave the company. Our secret is simple — and generally applicable. When we’re renewing, we’re truly renewing, so when we’re working, we can really work.

                                   -- Tony Schwartz, CEO of The Energy Project, in a New York Times column (2/10/13)