There is something about the human condition that turns on when the impossible becomes possible. There is something that happens inside of us physiologically that spurs us on when we know something is possible. Think about the the progression of extreme sports from year to year. The things that break boundaries one year are almost expected by most of the athletes the following year. Red Bull seems to be great at coming up with these kind of things. Weather it be skydiving form the edge of space, amazing rally car drifting.
Another example in the running world was the sub 4 min. mile by Roger Bannister
Check out an article about it here: http://www.nytimes.com/1996/11/03/sports/impossible-becomes-possible.html
kind of neat to see the progression when we put our minds to AWESOMENESS rather than creating divides and focusing on differences.