So are you saying that salvation is by works?
Salvation is a "Gift" from God. Working out your salvation through fear and trembling is making decisions to keep you from being tempted to fail. It means listening to God and doing what God tells you.
I do not watch x-rated movies, drink, smoke, cuss, let bad influences around me, don't hang out in bars, because these things (
for me only) could cause me to stumble and become strongholds in my life.
I know the entrapments of Satan and I stay away from them. I keep my mind occupied with God so things that can open doors to separate me from God don't happen.
God is my instructor. By doing those things I am obeying Him because He only shows me what to do in order that I don't fall away from Him. I do my best to let His Will be done.