Fear and Trembling

Philippians 2

¹²Therefore, my beloved,^(AA) as you have always^(AB) obeyed, so now, not only as in my presence but much more in my absence, work out your own salvation with fear and trembling, ¹³for^(AC) it is God who works in you, both to will and to work for^(AD) his good pleasure.

"work out your own salvation with fear and trembling". I'm still struggling to figure out what exactly that means. Kierkegaard wrote a book called "Fear and Trembling", the title of which was taken from this passage (I have this book on my bookshelf and have never read it...heh heh). In the book, Kierkegaard says, "Infinite resignation is the last stage before faith, so anyone who has not made this movement does not have faith, for only in infinite resignation does an individual become conscious of their eternal validity, and only then can one speak of grasping existence by virtue of faith." He uses the example of Abraham who resigned himself to give up his only son to God. Kierkegaard argues that only in being willing to give up all that we claim - all that we are - do we ever really approach "faith". Only when we trust everything to God do we come close to real, deep faith. After all, the meaning of the word faith is "complete confidence in a person, plan, etc.".
Maybe I should read this book (since I do alread own it). Or maybe I should spend some time talking with the Author of Faith...
I'm still wrestling with this phrase...Lord, help me to understand.