In our society something we see often is miserable people who have no real reason to be unhappy. Even talking to them is depressing. And when you try to find out why they feel the way they do – they don’t know either!
Frankly, I don’t think this video explanation works for everyone, but in my own experience, I can think of dozens of people I have met for whom it does offer a genuine explanation. I am sure you can attest to this yourself.
If you are unhappy more often than you can justify, perhaps you should take stock of your expectations.