Isaiah 26:3 - "The steadfast of mind You will keep in perfect peace, because he trusts in you."
Perfect peace comes to us IF we keep our mind on G-d. The storms come when the enemy intrudes on our minds. Have you ever noticed how pity parties are very lonely parties? You're the only one invited to the enemies' party. And boy does he take liberal license with our mind when we attend his party of one. He lies to us, he discourages us, he makes our minds focus on all that's bad in our life and he occupies our thoughts so completely that our peace vaporizes.
We need to "take every thought captive" (2 Cor 10:5) and submit it to our Holy G-d who is "able to do far more abundantly beyond all that we ask or think, ACCORDING TO THE POWER THAT WORKS WITHIN US...." If our minds are steadfast on G-d instead of on the things that are tormenting us, that power (HIS power) will work within us to defy the enemy of our soul who wishes to keep us in bondage.
But I admit, it is so hard when our minds slip and we are reminded of those things that aren't right in our world....they can get us down and make us so quickly forget the promises we need to remember. But how my heart rejoices with the truth when I allow the L-rd to minister to my spirit and remind me of all His wonderful promises He has granted me as His child and heir to the kingdom. My mind once again regains that "perfect peace."
John 14:27 - Peace I leave with you; My peace I give to you; not as the world gives do I give to you. Do NOT let your heart be troubled, nor let it be fearful.