Deep seated resentment can cause arthritis and other physical ailments. Jealousy, anger, rage, unforgiveness and other powerfully destructive emotions can wreck havoc on the human mind and body.
There are those with long standing resentments that have caused years of maladies in the body. When this type of resentment continues for years cancer may eventually manifest.
Holding onto grudges and unforgiveness is bitter pill that is turned inward not external to the ones who have inflicted harm. Perpetrator may not care or even know that someone hates them. Damage is inflicted on the one who hold resentment internally.
Here's a great way to describe bitterness "it's like drinking poison and expecting the OTHER person to die".
Life is too shot to hate other people. If one is full of hatred to be sure bitterness is hiding within the soul. If unforgiveness has been given years to fester bitterness has developed.
The remedy to a healthy mind and body is to let go, forgive, turn the person over to God and stop trying to be one. Letting go and forgiving is a process. Over time of consciously releasing someone in the mind will eventually end the constant obsession of evil thoughts and churning of the soul.
Healthy mind = healthy body. Live your life and let others live theirs. Everyone will give an account of life here on earth