“Unselfishness is the key to success in higher life.”
Living Hinduism ( Page 151 )
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Swami Samarpanananda 24
Monk, Author, TeacherRelated quotes

Variant: Success is not the key to happiness. Happiness is the key to success. If you love what you are doing, you will be successful.

[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]
Source: https://www.google.com/books/edition/What_Is_E_Commerce/PkPhDwAAQBAJ

“The key to success is failure”

“I don't know the key to success, but the key to failure is trying to please everybody.”
Originally from Herbert Bayard Swope (1882-1958); often attributed to Cosby, he actually cites this as a sound advice he once read elsewhere, in "Dr. Bill Cosby" in Ebony, Vol. 32, No. 8 (June 1977), p. 136
Misattributed

“The key to growth is the introduction of higher dimensions of consciousness into our awareness.”

“the 10,000hr rule is a definite key in success”
Source: Outliers: The Story of Success