You may consider yourself a fitness powerhouse—persistent, super fit, and always ready for the next adventure. But when was the last time you’ve actually challenged your athletic abilities? Your local gym might have a lot to offer, but regular weight lifting sessions can get monotonous. If you’re looking to push yourself outside your comfort zone, consider registering for some of these exciting obstacle course races. Some may fit your interest, while others might just scare you to death.

SPARTAN RACE

As one of the world’s most popular race course, Reebok’s Spartan Race offers three different courses: the Spartan Sprint, Spartan Super, and Spartan Beast. There are over 20 obstacles to hurdle, and each of the three different courses are timed and vary in distance. The race as a whole is designed to put both your physical and mental abilities to work, and provide an unforgettable experience that’ll enhance your fitness like no other.

Next race: June 17, 2017. Register here

(Pro tip: If you’re looking to start off light, register for the spartan Sprint. It’s the shortest of the brand’s three main courses.)

SAVAGE RACE

Savage Race isn’t equipped for everyone, but it provides you with a good balance between work and fun. This course stretches six miles, and has 25 different obstacle courses that put you through hell. Whether you’re climbing over fences in water, or sprinting over a quarter pipe, this course has just about everything.

Next race: June 17, 2017 Register here

(Pro tip: If you’re considering training for this race beforehand, download their training guide here for free.)

TOUGH MUDDER

Tough Mudder offers nearly ten different races, most of which are over ten miles long. The race gives you a chance to test your physical endurance. These courses are crafted to overcome some of the most common human fears such as heights, fire, and getting covered in mud.

Next race: June 17 and 18, 2017. Register here

(Pro tip: The key to winning this race is team work. If you’re lucky enough to make it to the finish line, they will induct you into their Tough Mudder Legion.)

CIVILIAN MILITARY COMBINE

If you’re looking for a more military-style adventure course, Civil Military Combine might be the course for you. Also known as CMC, It is the only obstacle course to include "The PIT," an area where you can go to physically prepare yourself for the race before it happens and keep your adrenaline levels and spirits high. The actual obstacle course is between four to five miles in distance, and includes over 20 military obstacles such as a wall climb and balance beams.

(Pro tip: You don’t have to go through this alone. The CMC offers you the opportunity to compete alone or with a team)

Next race: Sept. 16, 2017. Register here

THE ZOMBIE MUD RUN

The Zombie Mud Run is exactly what you think it is. Staged during a zombie apocalypse, this three-mile race will have you hurdling over both manmade and natural obstacles. Participants will wear a belt holding three flags representing three human organs: the heart, brain, and entrails. If each of these organs are eaten up by the zombies, you’ll lose the race. But don’t be alarmed, your actual organs won’t get eaten.

Next race: Oct. 14, 2017. Register here

(Pro tip: This isn’t your typical zombie action movie. Any contact with the zombies while completing the course will result in an automatic disqualification. )