Who said "When the going gets tough, the tough get going."?

This quote is attributed to Plutarch.

When the going gets tough, the tough get going. - Plutarch

"When the going gets tough, the tough get going."

Plutarch Perseverance

Historian Biographer Greece (Chaeronea) 46–120

"The mind is not a vessel to be filled, but a fire to be kindled."

"What we achieve inwardly will change outer reality."

"Be kind and merciful. Let no one ever come to you without leaving better and happier."

"Know thyself."

"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."