Who said "There's always room for improvement."?

This quote is attributed to Usain Bolt.

There's always room for improvement. - Usain Bolt

"There's always room for improvement."

Usain Bolt

Professional Sprinter Jamaican Born 1986 (age 40)

"To be a champion, you have to believe in yourself when no one else does."

"Don't think about losing. Just think about winning."

"I'm a living legend."

"Volleyball is my life."