To have purpose is to have drive.
It is difficult to find a purpose and once found, to serve purpose. Well, why is that? Purpose doesn't want to be served. Purpose wants to be fulfilled. Purpose doesn't know father time. Purpose doesn't know other priorities. It doesn't know what it means to have a lazy day, BIG Whigs, or GTD reviews. The only thing that purpose knows is its end.
In the words of the guy who inspired the slogan for Nike - "Just do it."