only IF you endure: Here is a trustworthy saying: If we died with him, we will also live with him; if we endure, we will also reign with him. (2 Tim. 2:1112).
And only IF you stand firm: [Jesus said] All men will hate you because of me, but he who stands firm to the end will be saved. Mark 13:13
And only IF you do what God wants: God will repay each person according to what they have done. To those who by persistence in doing good seek glory, honor and immortality, he will give eternal life. But for those who are self-seeking and who reject the truth and follow evil, there will be wrath and anger. (Rom. 2:68).
Clearly, what you do is rewarded by God. Like Paul, you must be working out my salvation in fear and trembling (Phil. 2:12), knowing that it is Gods gift of Grace that is working in you.
Fear and trembling is not doubt and anxiety but in reference to active reverence and spinelessness purpose of response to Gods Grace.
You are just making this up. Fear is fear. Trembling is trembling. It is the absolute fear and trembling that Pauls salvation might be lost.
Then said they unto him, What shall we do, that we might work the works of God? Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent. John 6:28-29