Because He cares

Nine words of instruction, five words of reason — and the reason is the remarkable part. Cast your care on Him, not because carrying it is inefficient, not because worry is bad for you (though it is), but because He careth for you. The invitation rests entirely on His affection.

“All your care” means the inventory is unrestricted. The reasonable cares and the embarrassing ones; the crisis and the nagging little dread you have never said out loud. Peter — who knew something about failing and being restored — sets no filter on what may be cast.

Notice too that casting is an action, not a feeling. You may not feel lighter immediately; do it anyway, by name: “Lord, I give You this one. And this one.” The feeling follows the practice. The care of you, meanwhile, was never actually your job — it was always His.