I recently corrected my sloth-like ways and became a runner. In fact, I ran the Boston Marathon this past April with a couple of my buds. On that day, I experienced my largest mood swing ever, from ridiculously pessimistic during the race, to euphoric upon completion. I definitely plan on running again next year. However, I pose a question. I have trained these past four months: stair running, hill running, long runs, tempo running. And my overall fitness level has improved. Howev...