“You will keep in perfect peace those whose minds are steadfast, because they trust in you” Isaiah 26:3 NIV).
Never dwell on your fear, your illness, your worry. Dwell on God's faithfulness. Think more of Him, and less of what you face in this life. He is the Great Physician, your healer. Dwell on that. He is your strength. Dwell on that. He is your rock no matter what comes against you. Dwell on that. He is your power to overcome adversity. Dwell on that. He is all you need at any moment. Dwell on that.
Even His most faithful children often do not claim healing for every part of their lives. Claim healing of your body, of your mind, and of your spirit. Love Him continually, and focus on Him always. Where you mind focuses, your heart follows. Allow Him to be what you can't be. Allow Him to handle what you can't handle. And then no weapon that comes against you will harm you.
You will know perfect peace no matter what. Dwell on that.