Many years ago, when I was in my teens, Dr. Don Johnson, a well-known, sports physician and father of high school friend of mine, talk to me about the importance of exercise. He told me that since we do a lot of mental work during the day, we need to exercise every day to work our bodies. He also told me that there are different kinds of exercise. Some exercise, like weights stress the muscles and cause them to get stronger, while other types, he called them zen exercises, are critical for relaxing the brain. Sports like running, cycling, rowing, he said, were zen exercises, because they were rhythmic and allowed you to relax the mind and recharge after a taxing day. I have always considered that very useful advice.