Considering about 16 years of research and based on religious evidence, one of the methods of mental relaxation that can save people from rumination and stress is to avoid hatred. In life, many conditions make us angry. Failure to "manage anger" turns anger into grudge. The spiteful man is constantly thinking about the damage and constantly thinking of revenge.
The malice create rumination, anxiety and depression . Then hatred causes sleep disturbance and then memory impairment occurs.
If we can forgive others, we will be relaxed. If the caused damage is so severe, it should give God and ask God for help.
The Qur'an says that: the remembrance of God is peaceful.
One of the ways to relieve stress can be to regulate off-task associative thinking. This can be done by meditation (either open or focused) to clear away the clutter inside the mind. Do not suppress the thought, just witness it without processing. Just let it come and go. Suppressing thoughts can have negative effect. Once you are able to regulate the thoughts, you have hold over processing what you want to process and let go the other thoughts.
There are various meditation techniques other than this exercise to overcome stress.
Mediation and practicing mindfulness and positive psychology can reduce the stress. In various research, mindful mediation has proved to reduce stress among human service professionals.