It is very important to realise the person showing signs of rage on the road, will not be thinking clearly. He will also not be acting rationally.
Make sure to avoid eye contact
Try to let it go. Do not take it personally. The action is not against you as person.
Keep yourself as calm as possible. Take a deep breath in and out and talk yourself into a calmer state or turn your music louder.
Ask yourself the question "is it really worth to retaliate? I'm sure your answer will mostly be "no"
If necessary and if possible, pull off the road and pull yourself together. The alternative is to slow down and cool down.
If the person is chasing you, drive to the nearest SAP offices and also try to remember his registration number.
You are not going to get the other road user to change his ways. You are only in control of your actions and the effect that you have on your health..