Updated: 05/29/2017
  If you look through the writings of those who found
  success, often great success, a key term found
  often, and sometimes repeatedly, is persistence.

  They may not explicitly use the word persistence
  but the message is there. Perhaps it's "Don't give
  up." or "Keep focused on your belief and passions."
  but it is still a driving persistence to achieve.
  Thomas Edison explained to a reporter he had NOT
  failed as he discovered 1,000 ways an electric light
  bulb did NOT work. Sometimes the path to success
  is trial and error, ruling out what cannot or does
  not work to arrive at something that brings change
  in great ways that were not imaginable before.
  The challenge is often overcoming our own doubt. 

  There are many quotes from many notable people across many professions, time periods, continents,
  religious and political beliefs, education levels, and on and on yet their message is consistently in the
  same tone and message.  A collection of quotes on persistence can be found at
  Perhaps no other word creates more power to overcome evil or improve the world than persistence.

  Never, ever give up (15:35)  |  TED, Diana Nyad                                                                                                       12/00/2013
  In the pitch-black night, stung by jellyfish, choking on salt water, singing to herself,
  hallucinating … Diana Nyad just kept on swimming. And that's how she finally achieved
  her lifetime goal as an athlete: an extreme 100-mile swim from Cuba to Florida -- at
  age 64. Hear her story.