"Do not give your attention to what others do or fail to do; give it to what you do or fail to do." 

-Dhammapada

"Failure is an attitude, not an outcome." 

-Harvey Mackay

“Many of life’s failures are experienced by people who did not realize how close they were to success when they gave up.” 

-Thomas Edison

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

-Thomas Edison