I sit on a man's back, choking him, and making him carry me, and yet assure myself and others that I am very sorry for him and wish to ease his lot b… - Leo Tolstoy

Pure, perfect sorrow is as impossible as pure and perfect joy.

"What's this? Am I falling? My legs are giving way under me," he thought, and fell on his back. He opened his eyes, hoping to see how the struggle of the French soldiers with the artilleryman was ending, and eager to know whether the red-haired gunner artilleryman was killed or not, whether the cannons had been taken or saved. But he saw nothing of all that. Above him there was nothing but the sky — the lofty sky, not clear, but still immeasurably lofty, with gray clouds creeping quietly over it.

No matter what the work you are doing, be always ready to drop it. And plan it, so as to be able to leave it.