The Unicorn and the Boston Marathon
The Boston Marathon medal displays an image of a unicorn. The image is meant to symbolize the pursuit of something that can never be caught/achieved. It represents an ideal goal of those who view a fast time as a mark of achievement, and we obviously admire any runner who pursues his or her goals.
The Donkey/Mule and the TSFB Marathon
In contrast, the mule is meant to represent stubbornness. Many average runners see the marathon as a chance to test their will. Because they spend more time on the course, they may face more adversity, and it may take more determination and persistence to finish the race. In the case of this marathon, stubbornness will more than likely determine the winners.