The human heart is a life-giving organ of the body. It is an organ upon which the entire body system depends. The Scriptures talk a lot about the spiritual 'heart' being the powerhouse and the command center of a human being (Jeremiah 17:9, Luke 6:45, Matthew 15:19); it can influence our attitude, morals, and values. Usually, the word heart is metaphorically used in the Bible to mean the mind, which is the center of the human soul.
The mind is the source of habits, thoughts, words, and actions that constitute our character. Our character, whether good or bad, can affect every aspect of our human life. We are saddled with the responsibility of protecting and guarding our minds because our minds determine the trajectory of our lives. 
We must be careful of what we allow into our hearts and the things we feed them with. Allowing corrupt things into our hearts via what we see, hear, watch, think, or even read can make us unclean and ungodly. When we obey and submit our thoughts, emotions, and will to the authority of God's word, our hearts are guarded from the corruption of the world. Our actions and decisions are projected in the right direction in life because our hearts are in the right place.

Dear Heavenly Father, I thank You for the salvation of my soul. Thank You for the gift of the Holy Spirit who works within me, transforming me to become like Jesus. As I give myself continually to the word of God, cleanse my heart of every corrupt thing that has found its way into my heart. Help me to submit to the sanctifying work of the Holy Spirit as I obey every instruction He gives. Please protect me from any activity that feeds my heart with corrupt and ungodly thoughts.
In Jesus’s name I pray. Amen.