It was Simone de Beauvoir that warned me of the dangers of never-ending hunger and ambition. She warned against the urge to always ask "and then?", for it will lead me to realize that the goal I pursue is ultimately futile, for I will return to myself and to rest in my kingdom after my conquest.
I find that there is yet another danger, perhaps a more fundamental one, to having such goals. It is not to ask "and then?" in an attempt to progress from a goal - it is to try and make the ultimate goal large enough and worthy enough for one's self, and in doing so not take the first small step towards the larger goal - although this might just be another form of asking "and then?", except that in this case we do not look for chronological succession, but an increase in the gravity of the task itself.