Moses was eighty years old. He felt secure in his "routine" and din't feel the urge to set off in a new challenge. Often, we all settle into this mode. If there is difficult tasks to perform, let the younger do it ... I have done my part and just want to rest it out. Again, Moses shows us a great lesson to apply each to our lives. We are never over until we are over. God wants our service until the day we die.