Take Tina Vindum, for example: The turning point for her came one day while running on a treadmill, counting the minutes as they crawled by.
"One minute, two, three -- it was excruciating," recalls the 46-year-old former competitive skier, who was training near Lake Tahoe, California. "I kept thinking, I want to be out there."
After that day, she took her workouts into the open air, and thousands of people followed her. Vindum created Outdoor Fitness, a California-based program that teaches not just strength, endurance, agility, and balance, but also focus and mindfulness.
"Life is not linear, and our workouts shouldn't be either," says Vindum, one of the nation's foremost experts on green exercise and the author of "Outdoor Fitness." "We want to move in a way we're designed to, laterally and diagonally over uneven and changing terrain."
There are lots of reasons to take your fitness regimen out of the gym: fresh air, scenery, sunshine ... not to mention a better workout. That's because when you stick to the same old, same old on machines and flat surfaces, your body figures out how to cut corners and save energy, Vindum says -- and you're more likely to hit a plateau. But outside, it's a whole different story.
"You recruit more muscle fiber when you're outdoors on uneven terrain because you're using more fine motor skills, like the muscles in your ankles that keep you balanced, and a core that has to work harder for stability. And that means you're burning more calories."
Beyond the sheer physics of what tree climbing and hill running do for the body, Vindum can't say enough about what simply being outdoors does for the soul. Her own energy has soared, and she just feels happier. "The visuals, the texture, even the smells make it a full sensory experience," she says. "It got me to slow down and introduced me to a calmer way of being."
Research confirms what we've known all along: An outdoor workout can deliver even more psychological and emotional benefits than pounding the treadmill. And any physical activity in nature counts -- hiking, cycling, horseback riding, gardening, fishing. Here's some of what you stand to gain by heading outside.
Frances Kuo, Ph.D., a researcher and cognitive psychologist at the University of Illinois at Urbana-Champaign, has found that natural outdoor spaces can actually boost your concentration and your patience -- which can help put your biggest goals within reach.
Better Mental Health
A recent British review of studies on the impact of exercising in nature shows that a mere five minutes of outdoor activity can have a significant effect on self-esteem.
A 2001 review found that green spaces enhanced effectiveness in daily challenges by reducing mental fatigue.
More Joie de Vivre
Simply being in nature can trigger peak experiences comparable to a spiritual breakthrough, according to ecopsychologist John Davis, Ph.D., of Naropa University in Boulder, Colorado. You may even get a little weepy. Vindum calls it "tears on the trail": "When a client of mine started crying after our workout, she said she didn't know why," Vindum recalls. "She was just so happy."
Vindum calls exercising outside "freestyle fitness" for a reason: There are no rules. The simplicity and spontaneity of using what's in front of you are what make it all so much fun. She does, however, have a few tips to help you get the most out of your outdoor experience, and a few sample moves to try.
Don't push yourself too hard at first, Vindum says; you'll get stiff fast. Rotate your joints (ankles, wrists, shoulders, hips), take a few deep breaths to get oxygen to your brain and body, and walk for a few minutes to raise your heart rate and warm up your muscles.
Work Larger Muscles First
"Do your squats, lunges, or pull-ups earlier," Vindum advises. "Save your abs for the middle to the end of your workout, so you don't burn them out. You need them to support you throughout."
Tune In to Your Feet
"We're so connected to our hands, but our feet have just as many nerve endings," Vindum says. She suggests focusing on feeling the ground through your feet -- every little rock or acorn -- as you warm up. This will also help prevent tripping. (Want to go barefoot? Check out the pros and cons.)
Test Your Props
Part of the fun of free-styling is using whatever crosses your path. Just remember to test an object or surface first, Vindum says. "Avoid the abandoned playground, the splintery or unhinged benches. And don't go barefoot in sand or grass unless you're very familiar with the area."
Take It In
It's one thing to focus on fitness, but don't miss out on all the other pleasures outdoor exercise can bring. "There's really something to the sensory experience -- the visuals, the textures, the sounds and smells," Vindum says. "Snap some pine needles, eucalyptus leaves, or grass and really breathe them in."
Ready to get started? Try these 9 Outdoor Workout Moves: No Gym Required