Peace of mind is actually in your mind. What new thoughts would help you feel peace? What thoughts keep you from feeling peace and should be discarded?
Ponder on these words from the apostle Paul: "Finally, beloved, whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is pleasing, whatever is commendable, if there is any excellence and if there is anything worthy of praise, think about these things." Phil 4:8