Interesting information but as he said at the beginning - Just Do It!
I really don't pay any attention to the time of day. I take classes so I go when the class is offered. Can it really make that much difference?
Why we exercise and how we keep ourselves motivated is much more important. I do think that people start out gangbusters sometimes and then get burned out and quit many times. I know it seems running is the elite thing to do - the ultimate. If you run, don't be offended - what I am saying is that I think some take up running for the wrong reasons. It is not realistic for many of us. I read of many who injure themselves and I read of many who keep on even though they are in pain. What's up with that?