Who said "The hardest opponent is always yourself."?

This quote is attributed to Mike Tyson.

The hardest opponent is always yourself. - Mike Tyson

"The hardest opponent is always yourself."

Mike Tyson

Professional Boxer American Born 1966 (age 60)

"Discipline is doing what you hate to do, but nonetheless doing it like you love it."

"Fear is only in the mind."

"I'm the best ever. I'm the most brutal and vicious, and most ruthless champion there has ever been."

"You must believe in yourself when no one else does."