Proverbs 4:23; "Keep thy heart with all diligence; for out of it are the issues of life".
There are emotions of the heart as, the loving heart, fearful heart, heavy heart, angry heart, the grieving heart, troubled heart, repentant heart, and the humble heart. These and more are mentioned in the Bible.
The heart is the center of the human will. The Bible talks about the hardened heart, refusing to do what God tells us. The clinging heart, one that clings to God, if you cling to God you will want to obey Him. There is a heart that wants to seek the Lord. All of these take place in the human will.
When Adam and Eve chose to follow temptation it affected the human heart dramatically. With their decision the heart became filled with evil. Mark 7:21-22; "For within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, v. 22 Thefts, covetousness, wickedness, deceit, lasciviousness, and evil eye, blasphemy, pride, foolishness". A heart that is impure will corrupt one's thoughts, feelings, words, and actions. Matthew 12:34; "O generations of vipers, how can ye, being, evil, speak good things? for out of the abundance of the heart the mouth speaketh". If our heart is full of anger how can we say words of kindness or if our heart is full of deceit how can we speak with a truthful tongue?
We need to make sure our heart is a pure heart one that has love, joy, peace, longsuffering, gentleness, goodness, faith, meekness, and temperance, these are the fruit of the Spirit. If we have these in our heart it will keep us from having evil thoughts and words coming from our mouth. All the goodness from our heart will show in our actions and words.
We need to always guard our heart so no evil will be able to creep in and whatever we do will show we have love for our Lord Jesus Christ and others as well. Let the Light of Jesus Christ shine through us.
May you always know the love, joy, and peace of the Lord!