Who said the quote "It's not what happens, it's how you respond to it"?

Question

I need to know who said it so I can properly cite it.

Answer 1

This entire concept, which constitutes a hugely powerful shortcut for getting what you want, for living on a day-to-day basis with considerably more pleasure and satisfaction, was brilliantly defined by a man named Epictetus, who himself lived a happy, productive, mutually-empowering life. He taught the world so long ago -- and it still holds perfectly true now -- that
"When anything external distresses us,
it is not the event which causes us pain, rather,
our response to it... ... and this we have the power to revoke at every given moment."

Answer 2

The previous person answered quite well. I'll just offer up similar quotes for you to ponder.

“I am responsible. Although I may not be able to prevent the worst from happening, I am responsible for my attitude toward the inevitable misfortunes that darken life. Bad things do happen; how I respond to them defines my character and the quality of my life. I can choose to sit in perpetual sadness, immobilized by the gravity of my loss, or I can choose to rise from the pain and treasure the most precious gift I have – life itself.”
Walter Anderson

“There are two big forces at work, external and internal. We have very little control over external forces such as tornadoes, earthquakes, floods, disasters, illness and pain. What really matters is the internal force. How do I respond to those disasters? Over that I have complete control.”
Leo F. Buscaglia

“Words can never adequately convey the incredible impact of our attitudes toward life. The longer I live the more convinced I become that life is 10 percent what happens to us and 90 percent how we respond to it.”
Charles R. Swindoll