First quoted by Walter Winchell, "On Broadway" (7 Jan 1937)

Also frequently attributed to Mark Twain, Eleanor Roosevelt, and Ethel Barrett; the latter used it ("We would worry less about what others think of us, if we realized how seldom they do") in her 1968 book Don’t Look Now But Your Personality is Showing. See here for more information.

Variants:

• "You’ll worry less about what people think about you when you realize how seldom they do."
• "You wouldn’t worry about what people may think of you if you could know how seldom they do."
• "We wouldn’t worry so much about what folks think of us if we knew how seldom they do."
• "You wouldn’t worry so much about what people think of you, if you knew how seldom they do."
• "You wouldn’t worry so much about what other people think if you realized how seldom they do."

See also Johnson.