"The relation that exists between the mind and the body is very intimate. When one is affected, the other sympathizes. The condition of the mind affects the health to a far greater degree than many realize. Many of the diseases from which men suffer are the result of mental depression. Grief, anxiety, discontent, remorse, guilt, distrust, all tend to break down the life forces and to invite decay and death." 
In a recent study, scientist have proven that negativity literally makes cancer grow inside the body. This study stated that, " Everybody feels negative emotions once in a while, but these emotions have a stronger effect on your health than you may realize. Every time you think about regrets, experience resentment or replay bad memories in your head, your body suffers just as much as your mind. That’s why harboring negative emotions can lead to devastating long-term disease. But there is one simple solution: forgiveness." 
Researchers conducted a clinical study focusing on the blood pressure, heart rate, facial tension and sweat gland activity of 35 female and 36 male participants. When the participants were prompted to imagine granting forgiveness to a true-life offender , the responses were note worthy! The forgiving thoughts produced lower physiological stress responses, confirming that negative thoughts have and are ultimately responsible for the health of the body and its functions.
Unforgiveness is classified in medical books as a disease, according to Dr. Steven Standiford, chief of surgery at the Cancer Treatment Centers of America. He insists that refusing to forgive people who’ve done you wrong makes people sick and keeps them that way.
Our thoughts and emotions have widespread effects on bodily processes like metabolism, hormone release, and immune function, Simon-Thomas says. One theory is that when you're stressed or depressed, cortisol levels increase, making your immune system less able to control inflammation, which could lead to disease over time.
“Harboring these negative emotions, this anger and hatred, creates a state of chronic anxiety,” he explains.” Chronic anxiety very predictably produces excess adrenaline and cortisol, which deplete the production of natural killer cells, which is your body’s foot soldier in the fight against cancer.” 
Sin is the cause of this sickness and Satan would have it that our minds and ultimately our salvation, be destroyed by any means. Satan knows that, ..." your iniquities have separated between you and your God, and your sins have hid his face from you, that he will not hear." Isaiah 59:2 KJV. Unforgiveness keeps us away from God and he cannot hear our prayers, nor accept our worship. Christ says, "Therefore if thou bring thy gift to the altar, and there rememberest that thy brother hath ought against thee;" Leave there thy gift before the altar, and go thy way; first be reconciled to thy brother, and then come and offer thy gift." Matthew 5"23-24.
Recognizing the warfare for the mind and its ill effects on the body and soul, it's high time we make amends with those around us-starting in the home.
No worries though, as always, God has given us the remedy to this self developed, satanic instigated, mind sickness.
Here's the formula:
" Forbearing one another, and forgiving one another, if any man have a quarrel against any: even as Christ forgave you, so also do ye." Colossians 3:13 KJV
"If thy brother shall trespass against thee," Christ said, "go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother. But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established. And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican." Matt. 18:15-17.
Our Lord teaches that matters of difficulty between Christians are to be settled within the church. They should not be opened before those who do not fear God. If a Christian is wronged by his brother, let him not appeal to unbelievers in a court of justice. Let him follow out the instruction Christ has given. Instead of trying to avenge himself, let him seek to save his brother. God will guard the interests of those who love and fear Him, and with confidence we may commit our case to Him who judges righteously.
Too often when wrongs are committed again and again, and the wrongdoer confesses his fault, the injured one becomes weary, and thinks he has forgiven quite enough. But the Saviour has plainly told us how to deal with the erring: "If thy brother trespass against thee, rebuke him; and if he repent, forgive him." Luke 17:3. Do not hold him off as unworthy of your confidence. Consider "thyself, lest thou also be tempted." Gal. 6:1.
If your brethren err, you are to forgive them. When they come to you with confession, you should not say, I do not think they are humble enough. I do not think they feel their confession. What right have you to judge them, as if you could read the heart? The word of God says, "If he repent, forgive him. And if he trespasses against thee seven times in a day, and seven times in a day turn again to thee, saying, I repent; thou shalt forgive him." Luke 17:3, 4. And not only seven times, but seventy times seven--just as often as God forgives you.
We ourselves owe everything to God's free grace. Grace in the covenant ordained our adoption. Grace in the Saviour effected our redemption, our regeneration, and our exaltation to heirship with Christ. Let this grace be revealed to others.
Remember, " A merry heart doeth good like a medicine: but a broken spirit drieth the bones." Proverbs 17:22 KJV