The life of a time lord is a difficult one the Doctor knows this all but too well, the Kahler believe that when you die your spirit must make a journey and that it must carry all the souls of those who you have done wrong to , the Doctor would have many worlds that he would carry on his back ,he is old his eyes have seen many things some good but they have seen many many bad things the end of Gallifrey the death of his friends the end of many worlds and the end of many lives some people wish to be like the time lords they wish to live forever they wish to know anything and everything about the universe but the ability to live forever is bitter sweet. Yes you get to live forever but what would you rather do live a normal human life span and see you friends all during that life time or live forever and watch your friends die while you live forever without them. That is what the Doctor is faced with. You may be wondering how I know all of this. It's a simple explanation. Hello I'm Susan I'm a time lady come from the planet Gallifrey in the consolation of Kasterborous I'm 904 years old. And I'm the Doctor's sister