“The greatest discovery of any generation is that a human can alter his life by altering his attitude.”

"Man alone, of all creatures of earth, can change his thought pattern and become the architect of his destiny." Actually said by Spencer W. Kimball, twelfth president of The Church of Jesus Christ of Latter-day Saints, in his Miracle of Forgiveness (1969), p. 114. This predates any of the misquotations.
Other forms: "The greatest discovery of my generation is that human beings can alter their lives by altering their attitudes of mind." This is also misattributed to Albert Schweitzer.
James did say: "As life goes on, there is a constant change of our interests, and a consequent change of place in our systems of ideas, from more central to more peripheral, and from more peripheral to more central parts of consciousness."
Misattributed

Stanley
Alessandra
1995-12-07
Dmitri Volkogonov, 67, Historian Who Debunked Heroes, Dies
New York Times
https://web.archive.org/web/20110120220404/http://www.nytimes.com/1995/12/07/world/dmitri-volkogonov-67-historian-who-debunked-heroes-dies.html
.

As quoted in The Artist Observed: 28 interviews with contemporary artists (1991) by John Gruen, p. 3
Context: I feel ever so strongly that an artist must be nourished by his passions and his despairs. These things alter an artist whether for the good or the better or the worse. It must alter him. The feelings of desperation and unhappiness are more useful to an artist than the feeling of contentment, because desperation and unhappiness stretch your whole sensibility.

"Control of Human Behavior", item 160
Industrial Society and Its Future (1995)

Source: In Defense of Chaos: The Chaology of Politics, Economics and Human Action, (2013), p. 301