"Growth begins when we begin to accept our weaknesses." 
-Jean Vanier

"'I am this', 'I am that' is a sign of not enquiring, not examining, a sign of mental weakness or lethargy." 
-Nisargadatta Maharaj

"You cannot run away from weakness; you must some time fight it out or perish; and if that be so, why not now, and where you stand?"
-Robert Louis Stevenson

“Our greatest weakness lies in giving up. The most certain way to succeed is always to try just one more time.” 

-Thomas Edison