'Be Ready' in the Bible

He will go on ahead of the Messiah [See verse 76], in the spirit and power of Elijah, to rekindle the affections of fathers for their children, and [to influence] disobedient people to live wisely like righteous people. And he will prepare the people to be ready for [the coming of] the Lord."

So, you also should be ready, for the Son of man will return at a time when you least expect Him."