Here's one that feels inspirational today, after several days of long hard slogging at the day job:

"If a man is called to be a street sweeper, he should sweep streets even as Michelangelo painted, or Beethoven played music, or Shakespeare wrote poetry. He should sweep streets so well that all the hosts of heaven and earth will pause to say, here lived a great street sweeper who did his job well."
--Martin Luther King Jr. (1929-1968)