Just now, I have completed reading "The Upside of Your Dark Side," written by Todd Kashdan and Robert Biswas-Diener. This book has translated into Japanese, and it is available in Kindle Unlimited service.
Amazon.com: The Upside of Your Dark Side: Why Being Your Whole Self―Not Just Your "Good" Self―Drives Success and Fulfillment
The central claim of this book is to emphasize the benefits of your negative emotion such as anger, anxiety, and remorse. The author begins to indicate that modern society, especially in the US, is pursuing individual happiness too much. Everyone should be happy, pleasant, and cherish. Optimism and mindfulness are recommended by many leading people. However, these positive emotions are not always beneficial for the better life of ours, according to the authors.
For example, getting angry sometimes brings us a drive for improving the current situation. And remorse is necessary to learn better behaviors in the future.
In addition, the authors presented several results of experiments suggesting the efficacy of negative emotions. Optimists are often vulnerable to tough situations whereas pessimists are well tolerant to unexpected disasters. They emphasize the dangerousness of ignoring your negative emotions.
Mindfulness is also subjected of criticism. The authors agree with the importance of mindful thoughts. But actually, we usually behave mindlessly. Automated behaviors are often optimized to each of daily situation.
After all, the authors believe in the value of “wholeness,” which means balanced mind. You can accept your negative emotions as well as positive ones. Joy and meaning, novelty and stability are both elements of value in your life.
I totally agree the authors’ claim. You need not eliminate negative thoughts and emotions from your heart.
Though many experiments are referred in this book, source of each study are hardly clarified. It is not an exception of the same structure in a similar type of books. To be honest, I am doubtful about most of the results of studies introduced by the authors. But it is difficult to examine them. I think it is a serious flaw of this kind of books.