Let me demonstrate from my own life. Recently I have been feeling a little weary. Maybe I'm world-weary. Maybe now that my son is in remission and the most intense part of his treatment is over, I am experiencing emotions that were not released at the time. Maybe the epilepsy and developmental delay of my other son are taking a toll. Maybe it's hard for me to see people I care about making bad decisions. Maybe it's the chronic pain I suffer from. Whatever the reason, I've been feeling kinda... blah. And my SELF has been talking to me. Sometimes my SELF says, "why waste your time with people, focus on yourself" or "I want to be left alone" or even "maybe I'll die soon". So, while these moments come and go and are not ongoing, it still could develop into a more serious spiritual malaise if I were to give into it and neglect spiritual discipline. The good news is, by God's grace, I have not neglected my walk with Christ and I do talk back to my SELF. I remind myself of God's faithfulness, His nearness and that He is for me. His goodness and sovereignty over all things. I remind myself of His great love for me in sending His Son to rescue me out of the slavery of sin by His blood. I remind myself that He is my sufficiency and my treasure. Many other truths. I bring in passages like Romans 8, Ephesians 1, Colossians 3, Hebrews 12, John 10, etc. Then I am brought back to reality. The reality is that I am God's child and I am in Christ and that is the functional reality of my life. The things that my SELF tells me are "unreal" because, since I am in Christ and that is my true identity, whatever else my SELF is telling me is not true as far as my identity is concerned. While it is true that I have real feelings of discouragement, weariness, impatience, etc, I am not to be defined by those things. I am defined by Christ who is my life.
So, the next time your SELF starts talking to you, what are you going to use to talk back to SELF? May I recommend you start with Psalm 145 (below). This wonderful psalm is simply jam-packed with marvelous truths about who God is and what He has done and all that He is doing for you. You will benefit from it.