A man's concern, even his despair, over the worthwhileness of life is an existential distress but by no means a mental disease.
Viktor E. FranklAs for the concept of collective guilt, I personally think that it is totally unjustified to hold one person responsible for the behavior of another person or a collective of persons.
Viktor E. FranklTo the European, it is a characteristic of the American culture that, again and again, one is commanded and ordered to 'be happy.' But happiness cannot be pursued; it must ensue. One must have a reason to 'be happy.' Once the reason is found, however, one becomes happy automatically. As we see, a human being is not one in pursuit of happiness but rather in search of a reason to become happy, last but not least, through actualizing the potential meaning inherent and dormant in a given situation.
Viktor E. Frankl