Accept the lemons. What's done is done. ...
Learn from what's gone wrong. Consider failure a life lesson, in order to learn from it and make things better next time. ...
Spend some time figuring out what happened. ...
Work harder. ...
Don't "curb your enthusiasm." ...
Keep making lemonade
1::What’s done is done. There's no point in rehashing or worrying about your mistakes. The past cannot be changed. Instead, use your energy to impact the future.
2::Consider failure a life lesson, in order to learn from it and make things better next time. Instead of losing control, learn, learn and learn some more. And don't be afraid to do this, either. (You may not like some of your findings. But you can still learn from them.)
3::Analyze the situation and try to answer the questions that arise, as honestly as you can. Did you believe in yourself? At what moment did you feel doubt or fear of failure? Were you motivated enough? Did you act on the right information and use it correctly?

Was your goal important, relevant and achievable for you? Where and when did things go wrong? Maybe you need to re-create your goals and steps and take all your disadvantages into consideration.
4::Be better prepared next time. Use the information from your analysis, and try not to repeat any of the things that in your opinion led to failure.
5::If anything, be even more enthusiastic next time. Pat yourself on the back for having tried and vow to try again. Admire all your willpower, your desire to succeed, your perseverance. Keep your attitude positive, and stay cool. Now, you are stronger, smarter, better prepared, more experienced and even more motivated.
6:::Don't be afraid. Do it again. Do it now. Do it better. Do it right and finish what you’ve started. And celebrate every victory, especially the small ones.