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. (Philip 2:12)

Fear and trembling? Fear for what? 

Let us therefore fear, lest, a promise being left us of entering into his rest, any of you should seem to come short of it. For unto us was the gospel preached, as well as unto them: but the word preached did not profit them, not being mixed with faith in them that heard it. (Heb 4:1-2)

A similar sentiment of Paul the apostle in 1 Cor. 9:27

"But I keep under my body, and bring it into subjection: lest that by any means, when I have preached to others, I myself should be a castaway."

And also Jude verses 3-5

"Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort you that ye should earnestly contend for the faith which was once delivered unto the saints. For there are certain men crept in unawares, who were before of old ordained to this condemnation, ungodly men, turning the grace of our God into lasciviousness, and denying the only Lord God, and our Lord Jesus Christ. I will therefore put you in remembrance, though ye once knew this, how that the Lord, having saved the people out of the land of Egypt, afterward destroyed them that believed not." 

1 Cor. 10:1-12

"Moreover, brethren, I would not that ye should be ignorant, how that all our fathers were under the cloud, and all passed through the sea; And were all baptized unto Moses in the cloud and in the sea; And did all eat the same spiritual meat; And did all drink the same spiritual drink: for they drank of that spiritual Rock that followed them: and that Rock was Christ. But with many of them God was not well pleased: for they were overthrown in the wilderness. Now these things were our examples, to the intent we should not lust after evil things, as they also lusted. Neither be ye idolaters, as were some of them; as it is written, The people sat down to eat and drink, and rose up to play. Neither let us commit fornication, as some of them committed, and fell in one day three and twenty thousand. Neither let us tempt Christ, as some of them also tempted, and were destroyed of serpents. Neither murmur ye, as some of them also murmured, and were destroyed of the destroyer. Now all these things happened unto them for ensamples: and they are written for our admonition, upon whom the ends of the world are come. Wherefore let him that thinketh he standeth take heed lest he fall." 

Psalm 78:1-8

Maschil of Asaph. Give ear, O my people, to my law: incline your ears to the words of my mouth. 

Psa 78:2  I will open my mouth in a parable: I will utter dark sayings of old: 

Psa 78:3  Which we have heard and known, and our fathers have told us. 

Psa 78:4  We will not hide them from their children, shewing to the generation to come the praises of the LORD, and his strength, and his wonderful works that he hath done. 

Psa 78:5  For he established a testimony in Jacob, and appointed a law in Israel, which he commanded our fathers, that they should make them known to their children: 

Psa 78:6  That the generation to come might know them, even the children which should be born; who should arise and declare them to their children: 

Psa 78:7  That they might set their hope in God, and not forget the works of God, but keep his commandments: 

Psa 78:8  And might not be as their fathers, a stubborn and rebellious generation; a generation that set not their heart aright, and whose spirit was not stedfast with God. 

How to work out my salvation? 

Philip 2:14-16

"Do all things without murmurings and disputings: That ye may be blameless and harmless, the sons of God, without rebuke, in the midst of a crooked and perverse nation, among whom ye shine as lights in the world; Holding forth the word of life; that I may rejoice in the day of Christ, that I have not run in vain, neither laboured in vain."

2 Pe 1:5-8

"And beside this, giving all diligence, add to your faith virtue; and to virtue knowledge; And to knowledge temperance; and to temperance patience; and to patience godliness; And to godliness brotherly kindness; and to brotherly kindness charity. For if these things be in you, and abound, they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ."