Never Give Up.. Never Give In

I do my best to teach my Princes & Princess' that you should never give up and never given in. I am not always sure I get through to them, although I pray I do. Prince Dennis is having issues with not succeeding the first time he places his hand to do anything. I can't say that I did not see this trait forming in other arenas but I am very disappointed in the fact that he looses motivation after a loss of some sort. This could be wrestling practice, a video game, a test, etc... I have talked to I am blue in the face. Is there something else that I can do to keep him motivated to never give up and never give in? He has so much potential and so much talented but he has to develop it.