I thought that this was most inspiring by Martin Luther King Jr:
"If it falls your lot to be a street sweeper, sweep streets like Michelangelo painted pictures, sweep streets like Beethoven composed music, sweep streets like Leontyne Price sings before the Metropolitan Opera. Sweep streets like Shakespeare wrote poetry. Sweep streets so well that all the hosts of heaven and earth will have to pause and say: Here lived a great street sweeper who swept his job well. If you can't be a pine at the top of the hill, be a shrub in the valley. Be be the best little shrub on the side of the hill."