Remain unattached to the outcome

In a recent keynote speech "Eight Keys for Thriving in a Down Economy" by Jeff Schneider he mentioned the above.
No getting around it, this is easier said than done. You've put in all this research, work, arranging for and then aren't successful. Why the effort you say. I have all the criteria requested yet I was looked over or is that overlooked?
Your energy and effort needs to be doing your very best. If they didn't see that or weren't impressed then it isn't your fault. It may not be a good fit anyway. Now on to the next opportunity.
Just because we have the degree(s), time on the job, great referral letters doesn't mean we will be successful in our endeavor.
You can only achieve your desired outcome by being the very best candidate.