“The secret to success is to do the common things uncommonly well.”

My Life and Work (1922)

Positive Thinking Every Day : An Inspiration for Each Day of the Year (1993), "April 13"
Earlier variant: People become really quite remarkable when they start thinking that they can do things. And those who have learned to have a realistic, nonegotistical belief in themselves, who possess a deep and sound self-confidence, are assets to mankind, too, for they transmit their dynamic quality to those lacking it.
‪You Can If You Think You Can‬ (1987), p. 84

"What is strategy?," 1996

[Positive attitude key to success, says Gaur Gopal Das, https://timesofindia.indiatimes.com/city/nagpur/positive-attitude-key-to-success-says-gaur-gopal-das/articleshow/62501124.cms, Times of India, 15 January 2018]

As quoted in The Christian Leader, Vol. 37, Issue 7 (17 February 1934)

Said at Keswick, as quoted in The Education Outlook (1926) Vol. 78

Source: Speech at banquet of the National Union of Conservative and Constitutional Associations, Crystal Palace, London (24 June 1872), cited in "Mr. Disraeli at Sydenham," The Times (25 June 1872), p. 8.

In Herbert F. Vetter, " Not The Average Philosopher http://www.harvardsquarelibrary.org/unitarians/hartshorne.html", Harvard Magazine, May/June 1997, Volume 99, Number 5. On his selection to the Library of Living Philosophers.