Even when it's justified, nursing a grudge can harm your health. Try these five steps to make peace with your past.

Anger and hostility increase your risk of many health problems, from headaches and colds to hypertension and insomnia. Researchers have found that people stewing over a grievance have higher blood pressure, increased heart rate, more muscular tension, and even thicker blood and lower T-cell counts.

Anger triggers the 'fight-or-flight' response that has been hard-wired into humans since our caveman ancestors went hunting: your heart rate increases and your adrenal glands trigger production of the stress hormones cortisol and noradrenaline, making you alert. This is fine if you're staring down a woolly mammoth for a few seconds, but not if you're stuck in this mode day after day.

Your grudge could be caused by an extreme event, such as a betrayal; or it could be due to ongoing irritations, perhaps from a bullying boss. Whatever the cause, when you've been hurt, the last thing you feel like doing is forgiving — but if you do, you'll boost your health, slash stress and feel more in control of your life. These five tips can help.

1 Face it Don't repress or dismiss a painful event and say it didn't matter: it did. Give yourself permission to be insulted and furious. These feelings are a normal reaction to the grief you feel over the loss of a friendship or trust.

2 Get it out Put pen to paper – or fingertips to keyboard – and write and write and write. Say exactly what happened, how unfair or inappropriate it was, and how you feel. Once you name and own your feelings, it will be easier to see them as something that has passed, rather than part of your present.

3 Ask for help Whether you believe in God, angels, nature, the power of love or the strength of your own personality – or all of them – rally the forces for good in your life to help you through this.

4 Let it go Close your eyes and hold in your mind's eye the image of whatever it is that needs to be forgiven. Visualise this burden tied to your ankles, slowing your progress. Now, see yourself holding a pair of golden scissors. Say out loud, "I release you from the grip of my sorrow and hatred." See yourself snip the ties holding the burden to you – and walk on.

5 Be patient Learning forgiveness is like learning any skill: it takes time. If you don't feel any different right away, it doesn't matter. What's important is the fact that you have tried to change your life for the better. Forgiveness doesn't mean that what someone has done to you is right or that you can forget their actions. It has to do with changing your reaction to them. The paradox of forgiveness is that, when you no longer let anger and bitterness control you, you're the one who is healed.

How easy do you find it to forgive? Tell us below.