Watch over your heart with all diligence, for from it flow the springs of life.
Proverbs 4:23 AMP
The heart of a man is the man himself. It is the source of every human’s conduct. You can not be greater or lesser than the content of your heart. It is the seat of affection and passion, understanding, and will. Likewise, the heart is the faculty of thought and reason. To take away a man’s heart is to take away his life, for there’s no human being without a heart.
So, it is no lie that the heart indeed is the spring of life. The Lord Jesus, also talked described the heart as the source of every thoughts, including the evil ones.
But whatever [word] comes out of the mouth comes from the heart, and this is what defiles and dishonors the man. For out of the heart come evil thoughts and plans, murders, adulteries, sexual immoralities, thefts, false testimonies, slanders (verbal abuse, irreverent speech, blaspheming).
Matthew 15:18-19 AMP
The Lord Jesus was explaining to His audience where to focus on. He told them point blank what defiled a man. It was not the edibles, but the content of the heart. From the heart springs forth every kind of evil. If it is not pure, the thoughts will not be pure, neither the conversation nor the life in its entirety.
Just as great evil can come forth from the heart of a man, so can great good can come from the heart of the man who has believed the gospel–the regenerated man.
Everything is pure to those whose hearts are pure. But nothing is pure to those who are corrupt and unbelieving, because their minds and consciences are corrupted.
Titus 1:15 NLT
Meanwhile, God has promised, and His words can be trusted.
A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.
Ezekiel 36:26 KJV
However, it is important to note that this promise will only become a reality for those who have been saved. It is until we believed the gospel that this become a reality. We now have a new heart and a new Spirit. The thoughts of our nature, the thoughts of our Father can now spring out of us.
Therefore, it is now our responsibility to guard this heart of ours. To guard is to keep watch over. Though we have a new heart we are responsible for feeding it with God’s word so that we can know more about how He thinks, acts and speaks. We are responsible for keeping it away from influence of the world. We are to stand guard. To keep it off anything that contradicts who we are.
Finally, believers, whatever is true, whatever is honorable and worthy of respect, whatever is right and confirmed by God’s word, whatever is pure and wholesome, whatever is lovely and brings peace, whatever is admirable and of good repute; if there is any excellence, if there is anything worthy of praise, think continually on these things [center your mind on them, and implant them in your heart].
Philippians 4:8 AMP
It is worth noting that we have the help of God. Paul said this profound statement: “For it is [not your strength, but it is] God who is effectively at work in you, both to will and to work [that is, strengthening, energizing, and creating in you the longing and the ability to fulfill your purpose] for His good pleasure.” – (Philippians 2:13 AMP) We have the help of God as we stand guard over our heart.