Sample excellent response:
I turned a dissatisfying experience into a satisfying one when I was on the cross-country team in college and had never run the whole race in under 30 minutes. With only a month left in the season, I decided that I would run the race in 25 minutes. I ran every day to build up my stamina, and in that last race I achieved my goal time of 25 minutes, which was a very satisfying experience.