According to the the World Health Organization mental health is a state of well-being in which an individual realizes his or her own abilities, can cope with the normal stresses of life, can work productively and is able to make a contribution to his or her community.
In my opinion everybody should do everything in their power to achieve the best mental health possible. Physical health is far from enough if you do not have good mental health. There area many therapies available for improvement of mental health depending on the needs. In my field of chronic pain the following options are available:
1. Cognitive behavioral therapy (CBT). This is by far the most popular therapy in chronic pain and psychiatric diseases. Some information from the American Psychological Association here.
2. Acceptance and commitment therapy (ACT). A good lecture by Lilian Dindo here. Steven Hayes is an important figure in this field.
3. Internal Family Systems (IFS). A good introduction is this podcast episode with Tim Ferris and Richard Schwartz. This is a fascinating article about using IFS in chronic pain. More information in this post on Medium.
Any discussion about chronic pain and psychology should also include John Sarno. He helped thousands of people heal their chronic pain. A good lecture about his method by Ira Raschbaum here. For some people just reading his books completely resolved their long lasting pain.
One very debilitating condition is post-traumatic stress disorder (PTSD). There is a really good hope that psychotherapy combined with psychedelics is going to provide the most successful treatment soon. An overview in this podcast episode with Tim Ferris and Rick Doblin. A documentary showing the method applied on three people with PTSD is “Trip of Compassion”. One research article published in Lancet Psychiatry with treatment resistant patients in 2018 showed that more than 50% of participants did not meet PTSD criteria one month after the treatment : full pdf here.