Happiness is not natural. It's a mere human construct. It's a state of contentment discouraged by our genetic design because it would lower our guard against possible threats to our survival.
Chasing happiness is like chasing a shadow, but the positive thinking industry claims to know its secrets. Self-help was popularized by Norman Vincent Peale, an American minister. He invented "positive thinking", a concept now deeply rooted in our culture and steadily growing in influence.
Popular films and books are full of supposedly inspirational statements about how all you need to do is believe in yourself and then you'll be able to achieve anything in life. This is simply, and obviously, not true. I don't think there is a need to explain that many obstacles and misfortunes in life are unavoidable, or cannot be overcome. Our ancestors knew this, and many philosophical and religious traditions are based on the acceptance that being alive is a very challenging task, which comes with significant amounts of suffering. It goes without saying that we should do all we can to maximize our sense of wellbeing and minimize our suffering, but the end result cannot be a state of sustained happiness. We are not designed that way.
It could be argued that positive psychology blames those who are suffering for their suffering, as it is based on the idea that unhappiness is entirely avoidable. It follows therefore that an unhappy person must be inadequate and incompetent. Positive psychology encourages people who are struggling with a particular goal to persevere in the face of unfavorable possibilities, which is much more punishing psychologically in the long run than accepting defeat.
I believe that coming to terms with life as it is, and not as the happiness industry tells us it could be, will make us happier, and we will feel more at peace with ourselves and with the world. Unfortunately, the devil always has the best tunes.