The outcome of your life is ultimately influenced by what begins in your mind, by what you believe. A single thought can have a viral effect and take over other aspects of your life, ultimately transforming who you are, for better or for worse.
Real transformation happened after my old pattern of thinking and speaking was completely intercepted and replaced with the truth of God's Word:
"I am not timid, but I have power, love, and a sound mind" (2 Timothy 1:7)
"I am chosen, accepted, and adopted into God's family" (Ephesians 1:11-12)
"I have the Holy Spirit, so I am not a slave to fear" (Romans 8:15)
You will notice that each of these confessions is not a word-for-word quotation of the verse on which it is based. And that is OK.
Ask the Holy Spirit to lead you to scriptures that counter whatever situation or emotion you face. Then personalize the scriptures into confessions that you keep with you. Finally, speak them over yourself throughout the day, as often as necessary. This will help you begin to genuinely believe what you confess. You must identify with God's Word in order for it to change your identity.