Who said "Never give up, not even when giving up seems wisest."?

This quote is attributed to Courage the Cowardly Dog.

Never give up, not even when giving up seems wisest. - Courage the Cowardly Dog

"Never give up, not even when giving up seems wisest."

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."