It is not necessary to fret about everything; it is quite enough if the devil gets your mind rasped with one little worry, one little thought which destroys your perfect peace. It is like the polish on an exquisite table top. One scratch will destroy it and so your rest can be destroyed by a very little thing.
Perhaps you have trusted in God about your future salvation; have you trusted Him about your present business or earthly cares, your money and your family? What is meant by the peace that passed all understanding? (Philippians 4:7). It does not mean a peace no one can comprehend. It means a peace no amount of reasoning will bring. You cannot get it by thinking.
There may be perfect bewilderment and perplexity all around the horizon, yet your heart can rest in perfect security because God knows, He loves, He leads.
And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus.