Knowing When to Quit

How do you know when to say, “when!”  How do you know when it’s time to hang it up and quit?  Do you grit your teeth and say, “They will have to take me out feet first,” or do you see the handwriting on the wall, and you know it’s time to say, “when?”  Do you grasp the golden parachute, as they call a good retirement in business, or do you wait until they give you ten minutes to clean out your desk and a security guard walks you to the door and you are history?