Hi Junie, I agree with GrimReaper.  I think sometimes people do know that their time is near.  My father used to tell the story of his little Choctaw grandmother.  About a week before she died, she gave away most of her belongings, wrapped herself in a blanket her mother had woven, stayed mostly in her bedroom and passed quietly.  I think some people, especially those who have lived a long while and are in tune with their bodies are able to sense when it is their time.