How Exercise Can Strengthen the Brain
 I just want to add that I found it very difficult to stay on the treadmill for any amount of time due to boredom. I bought  a treadmill for home ( Sole F80 - very nice machine) and put a TV w/ cable and a dvd player in front of it. What really keeps me going though is the Xbox 360 with multiplayer matches of Call of Duty and a boom box w/ custom mixed CDs. I can get so immersed in that game that I don't notice the 40 minutes to an hour of running.