Dr Stan Steindl from UQ's School of Psychology spoke with ABC Everyday about resentment and provided some tips to help practice forgiveness.
He says resentment is a complex and painful human emotion.
"It relates to a bitter disappointment coupled with anger and fear about having been insulted, wronged or treated unfairly by another person," Dr Steindl said.
"Human resentment can often turn into vengeance motivations, and a desire to 'teach them a lesson' or get some sort of 'payback'.
"Chronic resentment can be a precursor to anxiety and depressive disorders, relationship distress and dysfunction, withdrawal and isolation and sometimes aggression and violence."
Identifying the threat and feeling of resentment is the first step in addressing it, says Dr Steindl.
Resentment is related to sympathetic nervous system activation, so we want to try to slow down the body and the mind by activating the parasympathetic nervous system. Activities like meditation, massage and deep breathing can help do this.
One exercise Dr Steindl recommends that can help ease body tension and calm the mind: Sit in an upright but relaxed position, relax your face, soften your self-talk so you're using supportive inner voice tones, and slow down your breath, breathing in for four and out for four.