Who said running had to be serious? From a zombie-themed race to a run that ends with lots of chocolate, here are six quirky ways to break a sweat and have some fun at the same time.

Related: The Boom Market for Niche Fitness Events

Run For Your Lives

Zombiephiles are chased by the undead and encounter obstacles like a blood pit, smokehouse and maze in this 5K race held at various locations nationwide. Once survivors make it to the finish line (the "Safe Zone"), it's time to celebrate at the Apocalypse Party.
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The Color Run

Billed as the "happiest 5K on the planet," this untimed race in more than 100 U.S. cities has only two rules: Wear white at the starting line, and finish splattered in colored powder. This year's events will attract more than 1 million runners, up from 600,000 in 2012.
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The Great Bull Run

Modeled after Spain's San Fermin festival, this quarter-mile U.S. version takes place in large venues (as opposed to city streets), allowing thrill-seekers to "grab life by the horns." More about avoiding getting gored than actual running, the race launched this fall in Virginia and will expand to more locations next year.
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Tough Mudder

Tough Mudder events are untimed 10- to 12-mile obstacle courses designed by British Special Forces to test "all-around strength, stamina, mental grit and camaraderie." Only 78 percent of entrants successfully complete each of the 20 to 25 challenges, which include plunging into ice water, climbing inclined monkey bars and sprinting through a muddy field of live wires. The race has raised more than $5 million for the Wounded Warrior Project.
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Warrior Dash

The 5K Warrior Dash is one of the largest and longest-running obstacle races, with locations worldwide. Participants test their limits in challenges involving water, fire, mud, ropes, tires and barbed wire. Warriors have raised more than $7 million for St. Jude Children's Research Hospital.
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Hot Chocolate 15/5K

Hot Chocolate races, which benefit Ronald McDonald House Charities, are 5K and 15K runs in major U.S. cities. Rewards at the finish line and after-party include hot chocolate, fondue and dippable treats.
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