A positive mental attitude does have benefits. Back before MRIs and brain studies, the Buddha listed the benefits of practicing metta meditation to turn the mind toward thoughts of loving-kindness. Anecdotal evidence -- and now scientific research -- confirm this.
Anger and sadness are an important part of life, and new research shows that experiencing and accepting such emotions are vital to our mental health. Attempting to suppress thoughts can backfire and even diminish our sense of contentment. “Acknowledging the complexity of life may be an especially fruitful path to psychological well-being,” says psychologist Jonathan M. Adler of the Franklin W. Olin College of Engineering.
But Pollyana is not the model for mental health. Ignoring or surpressing thoughts we consider bad or negative doesn't make them go away -- researchers found that people who tried to suppress a negative thought before sleep went on to dream about it. t also can lead to substance abuse as a way to avoid them.
“Taking the good and the bad together may detoxify the bad experiences, allowing you to make meaning out of them in a way that supports psychological well-being,” the researchers found.That is, of course, counter to our culture's emphasis on happiness, on making everything all good/all the time.
The key is to acknowledge the feelings, sit with the discomfort, and learn that -- like happiness -- it comes and goes. That's what we train in doing in meditation. (The article cites a 2012 study that found that a therapy that included mindfulness training helped individuals overcome anxiety disorders. It worked not by minimizing the number of negative feelings but by training patients to accept those feelings.)