Editors' note: Mayer became the CEO of Yahoo on July 17, replacing interim CEO Ross Levinsohn.
"When you do something you're not ready to do, that's when you push yourself and you grow," Mayer told the audience at the 2011 Fortune Most Powerful Women dinner in Palo Alto, CA. "It's when you sort of move through that moment of discomfort of, 'Wow, what have I gotten myself into this time?"