God speaks to us as we study His Word. Sometimes He speaks to us with a still small voice. When we listen and respond to His message, our hearts becomes tender---useable for the Lord's work.
If we don’t listen or respond to the message of the Lord, our hearts grow callused---insensitive to the spiritual things of God.
Believers must never reach the place where we lose our compassion for those who need the Lord, our prayers and love.
Psalm 139:23-24 Search me, O God, and know my heart: try me, and know my thoughts: And see if there be any wicked way in me, and lead me in the way everlasting.