Persevering in working out my salvation with fear and trembling means learning how to persevere in the waiting as much as I would in the activity or the persecution that I might endure. This would be quite difficult to do in my own strength, but, thankfully, I don't have to do it that way.

Philippians 2:13 (NIV) states, "for it is God who works in you both to will and to act according to His good purpose." God's work in me and His work alone is what places in me the strength to persevere in the waiting and places in me the strength to do what He alone could enable me to do. "...for without me you can do nothing." (John 15:5b - NKJV)