If you like the idea of taxing your body and seeing exactly how far it can go before giving out, a Tough Mudder is worth your consideration. Not only will you be tested physically, but you will be tested mentally too.

Completing this type of event takes all of the strength you can muster, which may make you wonder how many calories you’ll burn if you choose to participate. To figure that out requires that you take a look at what is involved in a Tough Mudder.

The Tough Mudder is a 10-12 mile (18-20 km) course that is loaded with obstacles—usually somewhere around 25—and each obstacle is designed to challenge you in some way. For instance, some require navigating through balls that are being thrust at you while trying to avoid the mud pit should you fail to avoid their hit. Another obstacle might involve gliding down a slide, beyond a lair of fire, testing your mental fortitude and willingness to “face the heat.”

So, how much energy will you expend on a course like this? The exact amount depends on your age, sex, height, weight, physical condition, and more, but a rough estimate is somewhere around 3,000 calories. Yes, that is a three followed by three zeros—three thousand.

If you are a 155 pound person, it would take you fourteen hours of walking or engaging in low impact aerobics to burn the same amount. Or, you could just put in 11 ½ hours rowing or bicycling if you want to don’t have that much time.

However, if you’re up for the challenge, then maybe you should sign up for a Tough Mudder course near you. One thing is for sure, it is something that you will never forget. Ever.