God's promise for our peace can be found in Philippians chapter 4.
Philippians 4:6-7 Do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and your minds in Christ Jesus.
God wants to be the source of our security. Worrying does nothing but tie up our souls. This passage directs us to instead bring our needs before God in prayer. The answer to our anxiety is trust in God, but as you address your cares, don't miss thanksgiving. Take a breath and start your prayers with gratitude, thanking God for who he is and for the gifts and grace you do have. It can put our problems, that once looked urgent and overwhelming, into perspective against our powerful and loving God.
If we do this, the promise in verse 7 is that the peace of God will guard our hearts and minds. I've had this described by friends as peace that makes no sense. We may seem to have all reasons for fear and anxiety, but if our thoughts and emotions are given to God, He becomes our refuge.
Lord, I cast my cares on you as you care for me. I thank you for your love, your gentleness with me, your rich mercy and for another day to enjoy so many things like my daughter, the sun light, the breeze. I don't want to fear the future and the diagnosis my wife has. I don't want to be anxious about the upcoming changes in our life. I thank you that you look over me and my family. Shelter my heart and mind with your peace beyond understanding. In Jesus, you son, I ask all this. Amen.