“What doesn't kill you mutates and tries again.”
Related quotes

“What doesn't kill you is gonna leave a scar.”

“They say that death kills you, But death doesn't kill you. Boredom and indifference kill you.”

“A prisoner of war is a man who tries to kill you and fails, and then asks you not to kill him.”

"This Is Not a Test".
She & Him : Volume One (2008)
“What doesn't kill us makes us funnier.”
Source: The Other Side of the Story

2010s, 2016, September, First presidential debate (September 26, 2016)