The victory truly is in Christ, what the Lord Jesus has done. His perfect life, His resurrection. The hope that He offers brings security. Assurance is ours as we trust in Christ as our only hope. We cannot drum up security or assurance. We cannot manufacture these things. Salvation is all of Christ.
so that by two unchangeable things in which it is impossible for God to lie, we who have taken refuge would have strong encouragement to take hold of the hope set before us. 19 This hope we have as an anchor of the soul, a hope both sure and steadfast and one which enters within the veil, 20 where Jesus has entered as a forerunner for us, having become a high priest forever according to the order of Melchizedek. –Hebrews 6:18-20 NASB95
Jesus has already gone ahead for us as He has become our Eternal High Priest according to the order of Melchizedek. The writer of Hebrews was getting the point across to these Jews that salvation lies in Christ Alone, His person and work. There's nothing you can add to Christ having brought the hope God the Father to us as a guaranteed promise. We serve a God that not only does not lie, but cannot lie.
Promises given by God to Abraham were sealed with a covenant sealed with God swearing by Himself. Isaiah chapter 6 shows us that He is Holy, Holy, Holy. He is righteous and there is no sin found in Him--not one ounce, not one drop of sin is found in this holy, righteous God.
All peace is found it would be found in Christ and it is found in Christ alone. Your security and hope are found in Him alone. Your Assurance is in the God that lives forever, who will never die. Christ is trustworthy; He will never lie and has promised that He would never change His mind towards us. You are safe in Christ, your Refuge. Run to Jesus in whom your security lies.
Go to God's word. Dig into the truth of the Scriptures to find the peace and assurance that you need to calm your heart, your mind. Learn to not trust in your emotions, but rather to trust in the written Word of God. We're geared emotionally but learn to trust in this Book of all books.