If you’re feeling a little unlucky today, you’re not alone. For centuries, "Friday the 13th" has enjoyed a mythical association with bad things happening, and it definitely  persists today. In fact, Friday the 13th came in at No. 17 on a list of 28 superstitions that people secretly believe in, according to a recent survey of more than 27,000 voters posted on Ranker, a crowd-sourcing website. (Knocking on wood snagged the top spot.)

So, where did the myth start? It's unclear when exactly Friday the 13th became it's own superstition, but the "bad juju" surrounding the number 13 stems from the early days of Christianity, Stuart Vyse, a psychology professor at Connecticut College, explained to USA Today. That's because 13 guests are believed to have dined with Jesus for the Last Supper before he was killed, with the traitor Judas Iscariot believed to be the 13th guest.

Geoffrey Chaucer's The Canterbury Tales, published in the 14th century, didn’t help the situation when Chaucer cast Friday as a day of misfortune. "On a Friday fell all the mischance," he wrote.

And much more recently, who can forget the Friday the 13th movies, and even the classic film Freaky Friday?

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This historical background, however vague, is the reason we feel like something terrible is going to happen every time the 13th of the month falls on a Friday, Matthew Hutson, science writer and the author of The Seven Laws of Magical Thinking ($14; amazon.com) explained to Health.

“We’re told that Friday 13th is unlucky, so that sort of puts us on guard and causes us to look for things that might be evidence of the preconceived notion that Friday 13th is unlucky,” he said. “You’re also more likely to interpret neutral events as bad because that also matches your biased notions.”

Luckily, us extra superstitious folks don’t have to hideout for the day to avoid our Friday the 13th fear.

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“You can also take a negative superstition and flip it around. So you could try to think of Friday 13th as a lucky day and to recall good things that have happened on Friday 13th in the past. Maybe a good friend that was born on Friday 13th or something good happened to you on the 13th of the month in the past,” Hutson said. “Forming these position associations can help to overwhelm the negative associations and help you feel less anxious throughout the day.”

But engaging in a little healthy superstitious belief isn't necessarily a bad thing.

"Interpreting something bad that has happened as something that was meant to be, may help you find a silver lining," Hutson adds. "There is research that suggests that people cope better and recover better from negative experiences when the view them as something that was part of the bigger picture."

At the end of the day, Hutson explained that as long as you are rational in your superstitious thoughts and they aren't affecting your ability to live, you have nothing to worry about.

"If you feel like touching your doorknob three times on the way to work improves your luck, then go for it, but if you feel like you need to touch it 3000 times or else the world will fall apart, then you should probably rethink your habit," he said.

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