KEATING: Boys, you must strive to find your own voice. Because the longer you wait to begin, the less likely you are to find it at all. Thoreau said, “Most men lead lives of quiet desperation.” Don’t be resigned to that. Break out! Break out!

Tom Schulman (b. 1951) American screenwriter, director
Dead Poets Society (1989)
    (Source)

See Thoreau.