The Big-5 of the Heart,or The five purposes of the Heart is :

1. To Love God.
2. To Trust is God.
3. To Think about God
4. To Believe in God.
5. To meditate on God’s word.

Matthew 22:37 KJVS (Love)
Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind.

Proverbs 3:5-6 KJVS (Trust)
[5] Trust in the LORD with all thine heart; and lean not unto thine own understanding.
[6] In all thy ways acknowledge him, and he shall direct thy paths.

Proverbs 23:7 KJVS (Thinks)
For as he thinks in his heart, so is he…

Romans 10:8-10 KJVS (Believes)
[8] But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach;
[9] That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
[10] For with the heart man believes unto righteousness; and with the mouth confession is made unto salvation.

Psalm 119:11 KJVS (Meditation)
Thy word have I hid in mine heart, that I might not sin against thee.
Psalm 19:14 KJVS
Let the words of my mouth and the meditation of my heart be acceptable in thy sight, O LORD, my strength, and my redeemer.

Jeremiah 29:13 NKJV says :
[13] And you will seek Me and find Me, when you search for Me with all your heart.

In these last days, we are reminded that :
“The heart is deceitful above all things, And desperately wicked; Who can know it? I, the Lord , search the heart, I test the mind, Even to give every man according to his ways, According to the fruit of his doings. {Jeremiah 17:9-10}. Therefore, watch and pray, lest you enter into temptation. The spirit indeed is willing, but the flesh is weak.”(Matthew 26:41).

I John 3:19-22 NKJV
[19] And by this we know that we are of the truth, and shall assure our hearts before Him. [20] For if our heart condemns us, God is greater than our heart, and knows all things. [21] Beloved, if our heart does not condemn us, we have confidence toward God. [22] And whatever we ask we receive from Him, because we keep His commandments and do those things that are pleasing in His sight.

Jude 1:24-25 NKJV
[24] Now to Him who is able to keep you from stumbling, And to present you faultless Before the presence of His glory with exceeding joy, [25] To God our Savior, Who alone is wise, Be glory and majesty, Dominion and power, Both now and forever. Amen.