What is special about the word “casting”?

The Greek language has a way of strengthening the force of a verb by attaching prepositions to the verb. In this case the preposition on as found in the phrase on him is repeated within the verb throw so that its force is strengthened; hence cast as translation. We might say, We are not to place our cares before the Lord but to hurl our cares before him. There is an intensity and an intentionality built into how Peter says this. He wants his readers, then, to be deliberate in casting their cares.

It must further be noted that the word casting is a participle that gives color to the preceding command, humble yourselves. That is, humble yourselves does not imply passivity, as if there is nothing you can do about your situation; on the contrary, every frustration and vexation you experience you may/must cast before the Lord. This instruction flies in the face of our default response to suffering, ie, the determination to do something ourselves about the suffering (for example, escape, like Hagar, or fight back or get bitter).