One day last week and again yesterday, I was able to run before class, lift weights after class -go to a meeting, then go swimming after the meeting and then do some studying. In other words, my three big cognitive or mental activities were split up with exercise, not just physical activity (walking from one to the other would be physical activity). Instead, I set time aside to systematically increase my heart rate and tone my body, lungs and heart.
This is my ideal type of day. I will as often as possible break my mental activities up with little walks or some activity. Because of the mix it up routine I feel confident saying that I am at the 95th percentile of productivity. By this I mean, if you assessed 100 people on level of productivity, only five of them would be more productive than me (and maybe less!).