Some of us are overly concerned with appearing as though we never make mistakes. First of all, everyone around us knows we are not perfect. And the closer they are to us, the more they know it. A mistake is valuable if we learn from it. If, in humility, we can admit our mistake, learn from it, make amends when we are able, we will actually become closer to those we are afraid of letting down. There is nothing more endearing than authenticity and a willingness to admit weakness and fallibility.
Who among us enjoys being around the "know it all," the "been there, done that," person or the one who has a comment about everything?
Is it not obvious that the person who must promote himself/herself so loudly has deep-seated insecurities?
I'm not saying that you shouldn't attempt excellence. I'm just saying that, in your quest for excellence, remain authentic, approachable, teachable, and humble, and you will achieve more than you ever imagined...whether you fail or succeed.