Who said "Never give up—you're made of tougher stuff."?

This quote is attributed to Flexo.

Never give up—you're made of tougher stuff. - Flexo

"Never give up—you're made of tougher stuff."

Flexo Perseverance

"Bending is an art, and I am its masterpiece."

"Why settle for one beautiful thing when you can have many?"

"A true bender never bends the same way twice."

"Shiny things call to those with refined tastes."

"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."