It's also known as "catastrophising," and it happens to many people at some point in their lives. It might be a result of your previous bad experiences that you can't shake, or it could be linked to mental health issues like anxiety or chronic depression.
According to Linda Blair, a clinical psychologist and columnist at the Telegraph, catastrophising is an unhelpful habit people fall into in some way.
"Nobody is born a catastrophiser," she told Business Insider. "Babies and not born catastrophising... it's a protective mechanism, because we think 'if I think the worst, then when the worst doesn't happen I'll feel relieved.'"
Unfortunately, life doesn't work this way. By thinking catastrophically, we are actually making things worse, because our unconscious mind doesn't distinguish emotionally between what we imagine and what really happens.
"You're living through an experience twice, and one of them is guaranteed to be bad, because you're thinking the worst," Blair said. "So in the end it really isn't very protective. It causes great anxiety, because the emotional side, the amygdala, it thinking that this is really happening, and it's terrible."
People may learn the habit of catastrophising because they've had a bad experience before that they didn't see coming. To protect themselves in the future, they start imagining the worst possible scenarios in every situation, because they don't want to be caught off-guard again.
They may think to themselves that going through the worst situation in their mind will mean they get it over and done with — but in reality, this isn't logical at all. Nobody can predict or prevent the future.
Other people catastrophise because it is what their parents did, and they copy the patterns of behaviour they saw growing up.
"You don't always have to have an experience that causes psychological problems," Blair said. "We tend to get a little hung up on that... but it could simply be because that's what you saw and that's what you copy."
Like any habit, catastrophising is hard to break. Habits are stubborn, and in many cases, people have behaved the same way for years, perhaps decades.
Blair said a bad habit is always ready to jump back into your life, especially when you get highly emotional. But the solution is to learn to be rational and calm.
For example, in the case of imagining a plane crash, Blair asks her clients to look at the statistics for airline crashes on their phone. Then, she tells them to look at the statistics for crashes with that particular airline.
"And I say ok, a minute ago you said you were 100% certain that this terrible thing was going to happen, what percent would you give it now? And it's always lower," she said.
People then tend to see how rewarding it is to focus on the logical answers, rather than letting their imaginations get carried away. The more impulsive you are, the more likely to are to slip back into old habits, Blair said, but it just takes practise and persistence to learn to slow down and go to logic first.
Another solution she recommended is making a list of your most calm and sensible friends, and telling them you may phone them once in a while, as you sometimes feel out of control.
"The best way to gain perspective [on your worries] is to talk with someone else and put it outside you," Blair said. "You don't have to rush to a therapist... but it's hard work. It takes a good season, a good three months, sometimes six months, to start to change a habit."
So the next time you sense yourself spiralling over the fact your parents are late and could have been in an accident, or even something smaller like the fact someone isn't texting you back, take a breath and try to think objectively. Also, be aware of the fact you're trying to change, because it's not easy to adjust our behaviour.
"You must be kind to yourself and patient, and recognise the more emotional you are the more likely you are to not remember to do it right," Blair said. "Then, when we're still and we're calm, and things are under regulation, we get a chance to be logical.