When Jesus speaks of the new heart, He means the mind, the life, the whole being. To have a change of heart is to withdraw the affections from the world, and fasten them upon Christ. To have a new heart is to have a new mind, new purposes, new motives. What is the sign of a new heart?– A changed life. There is a daily, hourly dying to selfishness and pride.
– Messages to Young People, pg. 72