Thou wilt keep him in perfect peace, whose mind is stayed on thee: because he trusteth in thee. Trust ye in the Lord for ever: for in the Lord Jehovah is everlasting strength. Isaiah 26:3-4
Why is "the righteous nation" (ver. 2) composed of people who are kept in "perfect peace"? It is because their minds are stayed on God. And why are their minds stayed on God? It is because they trust in him. Trusting in God leads to minds fixed on God which leads to hearts kept in perfect peace. Don't you want that? Then pay attention to the logic of the text!
It starts with trusting God. Of course, not just any god, but the true God, the "Lord Jehovah" in whom is "everlasting strength" (ver. 4). The gods of the nations are idols and can do nothing. The modern rejection of any God for the secular reliance on self is even worse. There is no wonder that we live in times that, despite the proliferation of psychologists and psychiatrists, are characterized by incredible levels of stress and anxiety. But instead of our penchant to trust in ourselves, the Scriptures direct our gaze to the true God who dwells in the heavens and does whatever he pleases (Ps. 115:3; 135:6), and who directs the affairs in this world so that he is ultimately glorified and his people blessed. Indeed, "blessed are all they that put their trust in him" (Ps. 2:12).
If we trust in the God of the Bible (and not a god of our own making), then our minds will be stayed on him. You can tell what your trust is in by what your mind dwells upon, especially when trouble is near. If your trust is in God, then your mind will be directed to him when fears arise. "What time I am afraid, I will trust in thee" (Ps. 56:3). To have your mind stayed upon God means that the determinative factor in how you approach and think about the problems that surround you is the character and power and the promises of God towards you. Do we do that? If not, then let us examine our hearts for what it is that we are truly trusting in.
When we learn to lean upon God in this way, trusting in him and staying upon him, then it is inevitable that God will keep us in perfect peace. I think this is very similar to what the apostle Paul is talking about when he says, "Be careful [anxious] for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God. And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus" (Phil. 4:6-7). This is the kind of peace that you want: not a peace that you work up, but a peace that God gives. And it is given to those who trust in him, whose minds are stayed upon him, and which is expressed in a commitment to give everything to him in prayer (cf. Ps. 55:22).
Perfect peace! Let us avail ourselves of this great and wonderful gift by lifting our eyes to the God of heaven from whom comes all our help.