Think hitting the gym is hard? Nature is a perfect training ground.

The editors of Women's Health magazine have five reasons for you to blow off the dark, dreary gym and enjoy some crisp air.

1. You'll go for longerLeave the magazines at home and head out for an exploratory run through your neighborhood. You'll be surprised how much faster time travels when you aren't in the gym. To top it off, a grueling workout may not seem so grueling. When you're distracted by the environment, you're less aware of your effort, such as how far you've run or how much your quads burn. Heck, you might even double your workout to 60 minutes without even knowing it.

2. You'll blast more caloriesIt's easy to get in a fitness rut when your body knows exactly what to expect from your gym machines like the treadmill, elliptical and stationary bike. The varied terrain of a park might be just what your body needs to challenge itself to move in varied, more complex ways. Factor in wind (Mama Nature's form of resistance training), temps and other external variables, and you can end up torching 5 to 7 percent more calories just by trading the treadmill for trails.

3. You'll save moneyGym memberships aren't cheap. They can drain your bank account -- Americans spend about $475 a year on their facilities, according to CNN -- which can feel like a real waste if you're more of a no-show than gym rat. The smaller investment in a home gym can even be a waste of money for some: American households spend on average $130 annually on sports and exercise equipment. Besides cutting your fitness bills, running out your front door can save you cash on gas.

4. You'll fight germsGyms aren't always the meccas of health we make them out to be. A whole slew of studies show that gyms are breeding grounds for germs and bacteria. You can avoid these hazards by washing your hands often, changing your socks daily, using foot powder, wiping down equipment before and after use, and wearing flip-flops in the shower. Or you can simply take your training to the streets (even Rocky left the boxing ring every once in a while to run around his 'hood). Indoor air is two to five times more polluted than outdoor air, according to a study from the Environmental Protection Agency. If you've ever walked into a stinky gym, you know exactly what's up.

5. You'll think more clearlyBreaking a sweat outside may make you smarter.

"Humans were hunter-gatherers and farmers for some 300,000 generations [and] have been industrialized for only six to eight, so we are outdoor animals living largely inside," says Jo Barton, lead author of a 2011 study that analyzed the mental health of 53 people who were involved in indoor or outdoor activities for six weeks.

"Closeness to nature increases our well-being," Barton added. "It has an immunizing effect by protecting us from future stresses and helping us concentrate and think more clearly."