"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." That's Philippians 4:6-7. Try immediately praying about an issue when you noticing yourself worrying about it; tell Him "Lord Jesus, I put this in your hands. If there's anything You want me to do about it, please show me now, but otherwise, please help me to simply trust You". Also, if something's really staying on your mind, there's a good chance that it's BECAUSE He wants you to pray about it
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