2 Samuel 12:22

He said, “While the child was still alive, I fasted and wept, for I said, Who knows whether the Lord will be gracious to me, that the child may live?’ But now he is dead. Why should I fast? Can I bring him back again?

Sometimes things die in our lives: relationships, jobs, dreams can all end. When they are yet alive it is good and right to fight for them and plead with God for them but once they are over we must, like David, accept The Lord's will for our lives and move on. We can not go on mourning for the dead thing or we will miss the new thing God is trying to do in our lives.