Who said "I believe in me."?

This quote is attributed to Bart Simpson.

I believe in me. - Bart Simpson

"I believe in me."

Bart Simpson Courage

"Eat my shorts!"

"Ay caramba!"

"Don't have a cow, man."

"Cowabunga!"

"Never let fear stop you from chasing your dreams."

"Courage is being afraid but doing it anyway."

"Sometimes you gotta do what you gotta do."

"Sometimes you have to be the monster to stop the monsters."