Who said "I may tremble, but I won't turn back."?

This quote is attributed to Courage the Cowardly Dog.

I may tremble, but I won't turn back. - Courage the Cowardly Dog

"I may tremble, but I won't turn back."

Courage the Cowardly Dog Perseverance

"Courage, the cowardly dog."

"What's wrong, Muriel?"

"Oh, the things I do for love."

"Stupid Eustace!"

"Perseverance is the key to success."

"Don't give up on what you believe in."

"I've been through worse."

"You learn to live with the pain."