“You are not here merely to prepare to make a living. You are here to enable the world to live more amply, with greater vision, and with a finer spirit of hope and achievement. You are here to enrich the world, and you impoverish yourself if you forget this errand.”

Misattributed
Source: Often attributed to Twain, but sourced to Robert J. Burdette, Quote Investigator http://quoteinvestigator.com/2014/06/06/world-owes/

Attributed

Misattributed
Variant: Don’t believe the world owes you a living. The world owes you nothing. It was here first.
Source: Often attributed to Twain, but sourced to Robert J. Burdette, Quote Investigator http://quoteinvestigator.com/2014/06/06/world-owes/

Source: Big Magic: Creative Living Beyond Fear

Give up the small life, the petty life, the mean life, the restricted life, the little personal life which shuts you in - give it up and follow the light of the Star within you.
The Masters and the Path of Occultism (1939)

Ibid., p. 27.
The Gist of Art (1939)

As quoted in Writers on Writing‎ (1986) by Jon Winokur.
Variant: If you ask me what I came into this life to do, I will tell you: I came to live out loud.

Volume 2: Lake of the Long Sun (1994), Ch. 1
Fiction, The Book of the Long Sun (1993–1996)

Source: The Alchemist