“Desire sets our compass, but real life steers our course.”

Desperation (1996)

This last line references the last line of his DNC speech in 1980 where he said "the work goes on, the cause endures, the hope still lives, and the dream shall never die."
2000s, DNC Speech (2008)
And this November the torch will be passed again to a new generation of Americans, so with Barack Obama and for you and for me, our country will be committed to his cause. The work begins anew. The hope rises again. And the dream lives on.

"¿No es lo mismo que suceda lo que deseamos, que desear lo que suceda? Lo que importa es que nuestra voluntad y los sucesos estén de acuerdo."
La otra aventura, 1968.

Many attribute this quote to Marshall, however, General Omar Bradley is the correct author. Statement by Bradley (31 May 1948), quoted in An Inconvenient Truth : The Planetary Emergency Of Global Warming And What We Can Do About It (2006) by Al Gore.
Misattributed

Source: Lavinia (2008), p. 66

Source: Cosmos: A Personal Voyage (1990 Update), Journeys in Space and Time [Episode 8], 54 min 55 sec
Context: Those worlds in space are as countless as all the grains of sand on all the beaches of the earth. Each of those worlds is as real as ours and every one of them is a succession of incidents, events, occurrences which influence its future. Countless worlds, numberless moments, an immensity of space and time. And our small planet at this moment, here we face a critical branch point in history, what we do with our world, right now, will propagate down through the centuries and powerfully affect the destiny of our descendants, it is well within our power to destroy our civilization and perhaps our species as well. If we capitulate to superstition or greed or stupidity we could plunge our world into a time of darkness deeper than the time between the collapse of classical civilization and the Italian Renaissance. But we are also capable of using our compassion and our intelligence, our technology and our wealth to make an abundant and meaningful life for every inhabitant of this planet.

Just for Animals; quoted in Souls Like Ourselves by Andrea Wiebers and David Wiebers (Rochester, MN: Sojourn Press, 2000), p. 16.

"A Snow Mountain", reported in Bartlett's Familiar Quotations, 10th ed. (1919).