If you look at a lower-level or immediate goal and ask, "Why are you doing this?" then you'll often find the answer will kind of jump up a level in the nesting. For example:
Why are you crawling in this sewer?
So I can escape the castle.
Why do you want to escape the castle?
So I can overthrow the usurper and restore the Queen.
But if we keep going:
Why do you want to overthrow the usurper and restore the Queen?
Um...
Which is how we get to the question of motivation!