Peace of Mind!
This is not something to be attained. Peace of mind is given to a person as a gift.
Peace of Mind is one of the Spiritual attributes given to God’s people. The rewards of a spiritual relationship with Jesus Christ are collectively called the kingdom of God, or Righteousness – Joy – and – Peace in the Holy Spirit, Romans 14:17.
Ro 14:17 For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost.
(KJV)
Since peace is a gift – naturally, the absence of this spiritual attribute does not come from a lack of effort on the part of a person seeking it, but from the lack of the primary relationship in life, namely a spiritual relationship with God through Jesus Christ.
Righteousness is the ability to do what is right. Upon reflection it is clear that if the ability to do what is right is a gift and we should learn what we must do to get it. Faith in Jesus Christ is the only way to enter the kingdom of God.