“In the Pregluton, there were no animals of plastic tubing yet. This initial period was marked by an absence of matter. Life then consisted exclusively of dreaming about life.”

Quoted in A Dictionary of Quotations, in Most Frequent Use by D.E. Macdonnel (1809) translated from French: Le bonheur de l'homme en cette vi ne consiste pas á être sans passions: il consiste à en être le maître.
Misattributed

"Men Made Out of Words"
Transport to Summer (1947)
Context: Life consists
Of propositions about life. The human
Revery is a solitude in which
We compose these propositions, torn by dreams, By the terrible incantations of defeats
And by the fear that the defeats and the dreams are one. The whole race is a poet that writes down
The eccentric propositions of its fate.

In p. 163.
Sources, The Yoga Darsana Of Patanjali With The Sankhya Pravacana Commentary Of Vyasa

Variant: You become what you think about all day long.

Lexie Darnell, Chapter 13, p. 205
Source: 2000s, True Believer (2005)
Context: In her new, more mature incarnation, she embraced the idea that maturity meant thinking about risk long before you pondered the reward, and that success and happiness in life were as much about avoiding mistakes as making your mark in the world.

Source: 1975, The Philosophy of Andy Warhol (1975), Ch. 7: Time
Context: Sometimes you're invited to a big ball and for months you think about how glamorous and exciting it's going to be. Then you fly to Europe and you go to the ball and when you think back on it a couple of months later what you remember is maybe the car ride to the ball, you can't remember the ball at all. Sometimes the little times you don't think are anything while they're happening turn out to be what marks a whole period of your life. I should have been dreaming for months about the car ride to the ball and getting dressed for the car ride, and buying my ticket to Europe so I could take the car ride. Then, who knows, maybe I could have remembered the ball.

Walking (June 1862)