KNOXVILLE, Tenn. — Thousands of people are training to run 13.1 or 26.2 miles for the Covenant Health Knoxville Marathon on March 31.

That's a lot of miles.

For many runners, it would be unbearable to run that far on an empty, quiet road.

"Oh my gosh, if it weren't for headphones and music and signs... it would be the most boring thing in the world," said Clayton Cook.

So picture this. You're running the marathon. It's mile four. Mile five. Mile 20 You're feeling the burn.

Then you see this sign that reads "This is a lot of work for a free banana."

You laugh because, yeah, it's so true.

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That laugh and that moment of reprieve from the pain of running is why Mercedes-Benz of Knoxville puts out dozens of witty signs every year.

"We feel when someone can read a sign that has a Chuck Norris connotation in it, it's fun, people remember those," said Steve Norton, finance manager for Mercedes-Benz of Knoxville.

They are the masters of the witty marathon signs.

Some signs have zombies, others reference Star Wars and use sarcasm and puns to put a smile on a tortured runner's face.

"They're funny and witty and quick and smart, it really lightens the mood," said Gina Overstreet with Mercedes-Benz of Knoxville.

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Clayton Cook works at Mercedes, too, and ran the marathon last year.

He said these signs served as unconventional motivators.

"Running is such a mental thing that you just have to push through, and those signs on the road -- they distract you and get your mind off what you're doing," said Cook.

The Mercedes team has had these signs on the marathon course for about four years.

The runners' appreciation keeps them coming back.

"People would run by laughing, they would say thank you, they would point and giggle, it was really, really great," said Cook.

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The Covenant Health Knoxville Marathon, Half Marathon, and Relay all start at 7:30 a.m. on Sunday, March 31.

If you want to run it and see these signs in person, registration is still open.