Joshua 8:31 (in part) . . . And on it they offered burnt offerings to the LORD, and they sacrificed peace offerings.  source 

Let me offer this: There must be a sacrifice for us to experience peace.
When peace of mind has fled,  we must lay something on the altar of sacrifice for peace to be restored.
Like what?
Unbelief.

And unbelief covers it all — anger, malice, fear, resentment, bitterness, faithlessness, striving, disputes, covetousness, etc. etc.

All our sins originate in unbelief.  That is not believing (trusting) GOD.
For starters, not believing HE is.
Or not believing He is good; not believing He loves us; not believing He is right and holy; and how about this, not believing He is incapable of doing us wrong.

Peace of mind comes when we believe GOD. Peace flees when we entertain doubt.
So what do we do? We return to the altar and lay down our unbelief again.

It’s called repentance.

Let me offer you two verses of Scripture that have helped me stay in peace more times than I can enumerate.