To laugh often and much; to win the respect of intelligent people and the affection of children; to earn the appreciation of honest critics and endure the betrayal of false friends; to appreciate beauty, to find the best in others; to leave the world a bit better, whether by a healthy child, a garden patch, or a redeemed social condition, to know even one life has breathed easier because you have lived. This is to have succeeded.

Ralph Waldo Emerson (1803-1882) American essayist, lecturer, poet
(Misattributed)

This is regularly attributed to Emerson, but has not been found in his work. The original appears to be a contest essay written by Bessie A. Stanley of Lincoln, Nebraska in 1905:

He has achieved success who has lived well, laughed often and loved much; who has gained the respect of intelligent men and the love of little children; who has filled his niche and accomplished his task; who has left the world better than he found it, whether by an improved poppy, a perfect poem, or a rescued soul; who has never lacked appreciation of earth’s beauty or failed to express it; who has always looked for the best in others and given the best he had; whose life was an inspiration; whose memory a benediction.

In 1951, Albert E. Wiggam, a newspaper columnist, wrote this similar passage, claiming it was an abridged version of something Emerson wrote:

To laugh often and love much; to win the respect of intelligent persons and the affection of children; to earn the approbation of honest critics and endure the betrayal of false friends; to appreciate beauty. To find the best in others; to give one’s self; to leave the world a bit better, whether by a healthy child, a garden patch or a redeemed social condition; to have played and laughed with enthusiasm and sung with exaltation; to know even one life has breathed easier because you have lived -- this is to have succeeded.

Variations of both quotations exist, but Wiggam seems to be the source of the Emerson reference. This was later cemented by Ann Landers producing the variation at the top of this post, citing Emerson but not Wiggam. She also at other times attributed it to Harry Emerson Fosdick and Bessie A. Stanley.

More information here:

• He Has Achieved Success Who Has Lived Well, Laughed Often and Loved Much – Quote Investigator
• Stanley, Bessie A. - "Success" (1905) | WIST