“I really do believe that if you don't challenge yourself and risk failing, that it's not interesting.”
Academy of Achievement interview (2006)
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Julie Taymor 38
American film and theatre director 1952Related quotes
"The Answer" https://www.poetryfoundation.org/poems/50088/the-answer-56d22cd8d69d0, p. 33
The August Sleepwalker (1990)

Letter to Michael http://www.lettersofnote.com/2011/01/dont-do-it-for-anyone-else.html
“If you don't believe in yourself, then who will believe in you?”
Attributed to Korda in The Power of Choice (2007) by Joyce Guccione, p. 52, the earliest occurrence of such phrasing yet located is by Martin Lawrence, in "What Up?" in Upscale : The Successful Black Magazine (February 1993), p. 79: "If you don't believe in yourself, then who will believe in you? The next man's way of getting there might not necessarily work for me, so I have to create my own ways of getting there."
Disputed

Herman Cain: I’m More Than the ‘Anti-Romney’
2011-10-05
Wall Street Journal
http://blogs.wsj.com/washwire/2011/10/05/herman-cain-im-more-than-the-anti-romney/
2011-10-07
Regarding the 2011 Occupy Wall Street demonstrations.

Mock them. Ridicule them. In public. Don't fall for the convention that we're all too polite to talk about religion. Religion is not off the table. Religion is not off limits. Religion makes specific claims about the universe which need to be substantiated and need to be challenged and, if necessary, need to be ridiculed with contempt.
Reason Rally, National Mall, Washington, DC,
http://www.youtube.com/watch?v=Dq7rHRplZKU
YouTube
Richard Dawkins and his Foundation at the Reason Rally
2012-04-07

Reason Rally, National Mall, Washington, DC,

TV Series and Specials (Includes DVDs), Derren Brown: Séance (2004)