'Casting down arguments and every high thing that exalts itself against the knowledge of God'! This is a battle many believers struggle to overcome. But I have a good news for you. Contrary to what many think, this isn't so much about fighting the devil (& his fiery darts). The truth is Jesus has already won it for you on the cross. The devil cannot do anything to you if you don't allow him. Such is your authority in the spiritual realm!
So, what is the real battle then? It's a battle of 'believing that the battle has already been won'!
Under the covenant of grace, know that all is well with you and there's really nothing wrong with you, because you are in Christ. God sees you the way He sees His Son Jesus, and because He has accepted and is pleased with His Son, He has also accepted you and is pleased with you! That's exactly what being 'in Christ' means.
So, believe that all is well with you, in spite of all those medical reports you may have received, or despite whatever people say about (against) you! I've even known of some people receiving unsolicited 'prophecy' that their marriage is going to break, or they are going to die young, when the Bible clearly says, 'surely goodness (and yes, that includes in your marriage) and mercy shall follow you all the days of your life...' (Psalm 23:6) and 'with long life, I shall satisfy you...' (Psalm 91:16).
The key that makes all the difference here is, of course, in one's belief 'system'. You are what you believe. Choose therefore to believe in the truth of God's Word, instead of mere human words! Think of what God says about you, and not what mortal human says about you!
Now, many believers struggle to believe that God is really that good. They thought this is too good to be true! I used to think so too, until God drastically changed me and renewed my mind!
And the good news is when your thought life changes, everything else also changes! Your 'thought' is indeed like a magnet. It either attracts good things or it attracts bad things (including physical/bodily symptoms). Remember this: Flower attracts butterflies. Rubbish attracts flies.
Are you believing for jobs and better jobs today? Are you believing for divine health and healing today? Indeed, the battle for every believer under the covenant of grace is not so much about whether they'll win or not against the enemy, but to 'believe that all is well with them'! There's no question about winning or losing here, when you are in Christ. The battle is the Lord's, and He has already become the 'victor' for you!
So choose to have 'flower' thoughts about yourself, because that is the truth in the Word of God about you! You'll then 'attract' butterflies (yes, even 'spiritual butterflies', and this speaks of angels ministering and bringing 'goodies' to you). This is how God works for His people! And that's why your thought life is super-crucial at the moment, either in making you or breaking you. People of God, choose ye this day!
One of the best ways to have 'flower' thoughts is by meditating/muttering (speak under your breath) what God says in the Word. There is something powerful about 'speaking out' the Word by muttering it. When you read (or speak) it out, you are using your eyes to see, your mouths to speak, and your ears to hear. Faith (means: believing heart) then comes by hearing, and hearing by the Word of God (Rom 10:17). Three, instead of only one of your senses (if you do silent meditation), are actively taking in the Word!
Here are some of the personalized verses I've learned to meditate/mutter through the years (especially in times of temptation to fall into negative thoughts regarding any area of my life):
1. God knows my sitting down and my rising up. God understands my thoughts afar off. God's thoughts toward me are precious thoughts. (Ps 139:2,17)
2. The thoughts of the righteous are right. I am righteous in Christ and my thoughts are right. (Pro 12:5, 2 Cor 5:21)
3. God's thoughts for me are thoughts of peace that give me a future and a hope. (Jer 29:11)
4. I think only of those things which are true, noble, just, pure, lovely and of good report. I think of those things which have virtue and are praiseworthy. (Phil 4:8)
5. God keeps me in perfect peace because my mind is stayed on Him and I trust Him. (Isa 26:3)
6. The peace of God which passes all understanding guards my heart and my mind through Christ Jesus. (Phil 4:7)
7. I am not conformed to this world but I am transformed by the renewing of my mind, that I may walk in what is good, acceptable, and perfect will of God. (Rom 12:2)
8. I live according to the Spirit and mind the things of the Spirit. I am spiritually minded and have life and peace. (Rom 8:5-6)
9. I have put off the old man and put on the new man according to God's will for me, and is now renewed in the spirit of my mind. (Eph 4:22-24)
10. I set my mind on the things above and not on the things on this earth. I set my mind on the things of God. (Col 3:2)
11. I set my mind on the goodness of God, because it is the goodness of God that leads to a change in my life. (Rom 2:4)
12. God has not given me the spirit of fear, but He has given me the Spirit of power, and of love, and of a sound mind. (2 Tim 1:7)
Read/speak each of these personalized verses out and hear it many times, yes, 30, 50, or even 100 times or more if you may, till you are changed and renewed in your thought life according to the Word of God!
In conclusion, the key to overcoming negative thoughts is in making a choice to have 'flower' thoughts, not 'rubbish' thoughts; and that's how your thought life can be changed, and as a result, your entire life, even in every aspect, can also be changed! I've tasted and seen this truth in my own life, and praise God, I want to believe this for you as well. In Jesus' name. Amen.