Pedaling in place for an hour can make your weekly workout feel like it's at a standstill—in more ways than one. As the warmer weather begins to settle in, gyms are shaking up the typical exercise experience by trading in the treadmill for hills and trails to give its members a healthy, more stimulating sweat session.

Exercising in a natural environment can boost your mood, lower levels of stress and depression, and increase the likelihood of staying committed to your routine more than in an air-conditioned complex, according to a 2011 study published in Environmental and Science Technology. The Sports Club/LA and Reebok Sports Club/NY's Sports Coordinator Pam Opdyke took this into consideration when creating the New York club's programming for the spring and summer seasons. (Search: Find a gym near you with outdoor classes).

How can you lose weight running? With the Runner's Diet from Runners' World. 

"Any time you can have different things to get you coming back will make it easier to commit," says Opdyke. "The key to overall health and fitness is consistency and not letting it slip." The Clubs' triathlon training program is just one example of a class that is designed to amp gymgoers' endurance with loops and sprints in a challenging and freeing environment. (If you want to try running a marathon or a half-marathon, here are the best races for beginners).

But providing a similar surrounding to the outdoor event isn't Opdyke's only concern. Cabin fever is a condition that infects many as temperatures heat up, and catering to that need is a goal she sees as becoming more of a recent demand. "The biggest thing that I see right now is people wanting more group classes," says Opdyke. "Working outside is something that goes hand in hand with that." 

For Richard Gjonovich and his late wife, Elaine, breaking free of the traditional gym setup and moving the fitness experience out in the open was a need they recognized in their California community nine years ago. Now an established center, Outdoor Fitness Adventure Club gives those who would rather skip toying around with obscure machinery an opportunity to soak up the Vitamin D that only an outdoor boot camp or yoga class can provide.

Try one: The best new group workouts. And, take your fitness to the next level with the Men's Health Big Book of Exercises.

As its members clamber over rough terrain on a 90-minute hike, it's not just their balance and strength abilities that are developing. Gjonovich says that outside workouts lend themselves to building camaraderie and friendship within the group. "We found that people will quit a gym, but they won't quit their friends," he says. "They become committed to each other and the fitness aspect becomes secondary."

Burning calories also takes a back seat when it comes to Crunch's spring classes. The cardio movement class, BOING, puts a rock star twist on the aerobics routine when it moves from its indoor home to a nearby park. "If you look amazing in the Kangoo boots and you're doing some cool jumps in the air, that's something that people are excited about," says Marc Santa Maria, Crunch's Regional Director of Group Fitness. "The studios have a finite amount of space for you to play in, but in a bigger amount of space you can just do so much more." 

Both Santa Maria and Opdyke stress the importance of using gym equipment as strength and weight training tools, and also note the comforting privacy an indoor club affords. Testing those skills outside of the building, however, can offer added benefits that aren't as obvious. "It helps you understand the relationship to why you actually want to work out," says Santa Maria. "It's not just because you want to look hot, but that you want to be able to do things outdoors and in your daily life."