Who said "I learned that small acts of courage lead to big changes."?

This quote is attributed to George McFly.

I learned that small acts of courage lead to big changes. - George McFly

"I learned that small acts of courage lead to big changes."

George McFly Courage

"I'm your density. I mean, your destiny."

"This is heavy."

"There's that word again, 'heavy.' Is there something wrong with the Earth's gravitational pull?"

"I'm not very good at science."

"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."