Philippians 4:6 Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God. [7] And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus.
Another word for "careful" is “worry”. There’s nothing wrong with being concerned, it’s when your concerns control you that you have a problem.
Worry says, "If there is a God, He obviously doesn't care about me and my situation." Oh, but God does care, and He’s always near His children.
The Lord promises to replace our worries with His peace when we come before Him in trusting, humble prayer. Instead of worrying yourself sick about things you can't change, learn to lean on the Lord in prayer!