"Keep your heart with all diligence, for out of it spring the issues of life." (Proverbs 4:23)
The word, “keep” as used in the scripture above is the same used in Genesis 2:15: "Then the Lord God took the man and put him in the garden of Eden to tend and keep it." The word “guard” has a military connotation, which suggests protecting from attack or maintaining in safety from danger. This is the sense in which we’re to defend our hearts against wrong thoughts.
Wrong, unwholesome thoughts are enemies you must ward off continually. Read the James Moffat’s rendering of our opening verse; it’s profound.
(Proverbs 4:23, James Moffat's Version)
"Guard above all things, guard your inner self so you can live and prosper. Bar out all thoughts of evil and banish wayward words."
This doesn’t suggest or give room for you to be casual in dealing with wrong thoughts.
There’s a devil out there trying to send wrong thoughts into your heart through your mind; that’s his job. But you’re to bar his evil thoughts and banish his wayward suggestions by simply saying, “No” to them; erect a blockade against them.
God isn’t going to guard your heart for you. The responsibility is yours. But the good news is that you’re not helpless as to what to do. You’ve been equipped with “...the whole armor of God...” (Ephesians 6:11), and what you need to do is put it on and never take it off!
With your armor in place, you’ll be able to banish every evil thought or contrary idea that tries to assault your mind.
(2 Corinthians 10:4-5)
"For the weapons of our warfare are not carnal but mighty in God for pulling down strongholds, casting down arguments and every high thing that exalts itself against the knowledge of God, bringing every thought into captivity to the obedience of Christ."
I refuse to accommodate unwholesome, unhealthy, and noxious thoughts or to let the news of fear, poverty, economic meltdown, diseases, or death run my life or determine the circumstances of my existence. My mind is guarded by the Word and completely yielded to the right ideas, thoughts, materials, and messages. Therefore, I'm built up, edified, and strengthened in the Word, in Jesus' Name. Amen.
Further Study: Philippians 4:8; Romans 12:2