"You will keep the mind that is dependent on you in perfect peace, for it is trusting in you." Isaiah 26:3 (CSB)
This is a promise that you if you trust God, then you will have a steadfast mind. This means you can hold onto your inner peace no matter what is going on around you. You understand that God is in control and it does not benefit anyone to get all worked up and loose your peace over what you can't control anyway. It is a steadfast mind focused on God that keeps you in a state of peace.
Trust is being dependent on God. When your mind is fixed on God, then it becomes steadfast. You are propped up by Him when you can't do it anymore on your own. You don't experience the same kind of burnout because you stay in your lane. You know what you job or purpose is and you let God handle everything else. You don't get too caught up in the details because they can change or that was never under your control in the first place. You trust God to do His job perfectly, so you can rest in knowing you are doing your part.
Prefect trust in God provides Shalom (perfect peace). You have perfect peace because God is your everlasting foundation that will not break or shift. You are safe with Him. This peace gives you the freedom to problem solve, be creative, praise God, use your imagination, and more. It frees you from living in a box, even a self made box. God will never fit in a box. That means that His children do not fit into a box either. You have depth. Free yourself to explore who God wants you to be to the fullest.
You never need to doubt your relationship with God. You never need to doubt your salvation. Worship God freely and openly for all He does for you. When you sin, repent and get back in step with Jesus. Listen to the guidance of the Holy Spirit. He will push you well out of your comfort zone, but he will never lead you astray. God wants you to be all you can be. You need the mental freedom that comes from a steadfast mind to achieve that.
Isaiah 26:1-9 & 57:9