> It's an irrational response that persists even when there is no reason to be unhappy.

What if there is?

Generally, we are not very good at judging what makes us happy. Happiness research points to things that many of us are indeed missing in life: physical activity, social connectedness, interacting with nature.

The reason for unhappiness might also be internal; bad diet, lack of exercise, etc. throws your body's hormones off-balance, making you feel like crap and causing, quite predictably, unhappiness.