I wonder if physical activity correlates with education results. For example, in Finland kids typically walk or bicycle to school and are also actively running or playing on 15 minute breaks every hour.
I have to second the "Spark" recommendation. It presents the very compelling research behind exercise's cognitive and mood benefits. I've read many of the articles and books on this topic and Spark still included new information for me.
After reading it I decided to finally get on a religious exercise schedule and I've been on it for two months. The improvements to my will-power, focus, and mood have been tremendous.
As a side note: one thing that has helped me keep up the 5 to 6 exercise sessions per week is reminding myself that I'm only exercising for cognitive and mood benefits. This helps me personally not get distracted by other factors like fat-loss, improving running times, etc. If I added other non-brain goals, then it'd be easy to get bummed out and discouraged if I didn't achieve them, so I keep my goals purely brain focused. If those other benefits happen as a result of the exercise, then great, but they are not why I'm doing it.
I definitely think it does. Working harder in general drives better results, so I'm sure it's not only true in the workplace. When you have the energy, you're happier and want to do well. Period.
