The most important lesson I learned about failure is that without it, you do not truly understand success. When success comes too easily or too early in the process, we come to believe it is the natural state of things, and when failure comes at a later date in some form or another we are most often utterly unprepared.
My failures have opened my eyes to introspection and learning that has made me a better father, brother, friend, mentor... a better person.
This is not to say you should seek out failure, more about how important it is to stretch yourself and not be afraid of making mistakes. We need to empower our employees, associates, friends and children to understand that failure is incredibly valuable when you make learning part of the process.
"It's failure that gives you the proper perspective on success." ~Ellen DeGeneres