Keep thy heart with all diligence; for out of it are the issues of life. Proverbs 4:23 KJV
The heart involves the mind, emotions, and will. It is the center of our being. That is why God looks beyond our outward appearances into the heart. It is important to keep or guard it because whatever is in the heart will affect all the issues of our life. Jesus said, “A good man out of the good treasure of his heart brings forth that which is good; and an evil man out of the evil treasure of his heart brings forth that which is evil (Luke 6:45).” In other words, we cannot hide what is in our heart. Rather than trying to hide what is in it, a better course is to guard what gets in it. We put Scripture in the heart that it might block out desires and influences that will have a negative effect on our outward actions.
Lord, as David prayed in Psalm 139:23-24, search me, and know my heart, show me what is in my heart, and lead me in the way of life everlasting.