Up to 25% of the population suffers from or experiences ex conditioned if condition is serious enough. Blanche flower claims that when you ask what is the low point of life's satisfaction in the human life span, he wants to say it's mid life. You don't get a low point at midlife. You get this ever increasing emotional staility that starts from adolescence and just marches upward fairly linearly. For example, income correlates much more strongly with how you think about your life than how you feel in your daily life.