Up until yesterday, I would say probably not, but I was playing doubles in the finals of a tournament and we had 5 match points in the second set and lost. At first I just wanted to smash something but i managed to keep my cool and now I am laughing about it and I know that i'll be better mentally because of that loss. I also don't have to dwell on the missed match points, because my partner missed all of the volleys on match point. The other thing that helps is that for 2nd place we got 2 "rocks" glasses each, and the winners got 3 each, so we got almost the same prize, as dumb as it sounds. So, what was your hardest to take loss and what did it teach you?