Therefore, my dear friends, as you have always obeyed – not only in my presence, but now much more in my absence – continue to work out your salvation with fear and trembling (NIV)

Therefore, my dear ones, as you have always obeyed [my suggestions], so now, not only [with the enthusiasm you would show] in my presence but much more because I am absent, work out (cultivate, carry out to the goal, and fully complete) your own salvation with reverence and awe and trembling (self-distrust, with serious caution, tenderness of conscience, watchfulness against temptation, timidly shrinking from whatever might offend God and discredit the name of Christ). (AMP)

Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling. (KJV)