'Work' in the Bible

Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ:

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.

Because for the work of Christ he was nigh unto death, not regarding his life, to supply your lack of service toward me.