Paul speaks of the peace that Christ gives as if it were a ruler. Possible meanings are 1) "Do everything so that you can have peaceful relationships with each other" or 2) "Allow God to give you peace in your heart" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here "hearts" is a metonym for a people's minds or inner beings. Alternate translation: "in your minds" or "inside of you" (See: [[rc://en/ta/man/translate/figs-metonymy]])