My original comment does not cover depression. Without going into the underlying biology, it is safe to say that it is exceedingly rare for individuals with dep

My original comment does not cover depression. Without going into the underlying biology, it is safe to say that it is exceedingly rare for individuals with depression to be able to break out, because there are biochemical or structural changes in the brain that require either substantial changes in the individual's environment, or clinical intervention to overcome. There is also a fundamental difference between the experience of feeling happy and viewing something from a positive perspective. Even someone with depression could choose a positive interpretation for an potentially saddening event, but that choice alone would be unlikely to result in the experience of happiness, precisely because depression impacts the very ability to experience happiness, it is something more fundamental. There is also the question of whether depression makes it difficult to pick positive interpretations for events, but that is orthogonal to the point here.