They experience painful emotions, the difference between them and the rest was
that they recovered more promptly as a result of different interpretations.
So when they felt down, they were optimistic instead of saying "ok, so I'm going to feel down for the rest of the month",
they said "ok, so I'm feeling down, big deal.
What can I learn from it? What happen? How can I make myself feel better?"
And then they recovered more promptly than the pessimists, the people who remained depressed for a much longer time.
You see, events happen, things happen in the world, very often out of our control.
We don't create everything that we encounter.
And some of the events are bad, some are negative.
What matters more is what we do with them after, how we evaluate them.
And what happens is that our evaluation becomes a self-fulfilling prophecy, because a pessimist will say
"I'm in a bad mood now, it's going to last for a very long time, it's not going to go away",
whereas an optimist says "it's temporary, it's going to go away" and believes our self-fulfilling prophecies.
If I believe that it will last for six months, it's much more likely,
not necessarily, but it's much more likely to last for six months than if I say "that too shall pass".