San Francisco(CNN) How often do you get outside into nature, to smell the fresh air, walk among trees or kick up some dirt? If you're like most Americans, the answer is: almost never.
In the US, we spend a depressing 93% of each week indoors, a survey sponsored by the EPA shows. And according to the evidence, it's hurting our health.
Enter forest bathing.
The term comes from the Japanese word shinrin-yoku, which means "immersing in the forest atmosphere."
Since the 1980s, the Japanese have managed forests to help citizens relax and reduce stress -- and scientists have measured the results.
"Studies have shown that within 15 minutes of being in nature, your stress level goes down, your heart rate, blood pressure improves," said Dr. Nooshin Razani, a pediatrician and nature researcher with UCSF Benioff Children's Hospital Oakland. "If you're in nature longer, you can feel less depressed, less anxious. And if you're in nature for a few days, you have much increased creativity and cognitive ability."
And there's another big payoff, Razani said.
"Over the course of a lifetime," she said, "being in nature can lead to less heart disease, as well as improvements in how long people can live."
Being in the forest offers "a remembering for our whole being that we are nature and we're not separate from it," said Julia Plevin, founder of the Forest Bathing Club in San Francisco.
Plevin started the club in 2014 after suffering from anxiety during graduate school in New York. As part of her design school thesis, she studied the effects of being disconnected from nature.
She wanted to design walks to help people unplug from smartphones and reconnect with their own "nature." When Plevin took her own advice and headed outside, her mental and physical health improved, she said.
On a recent walk through San Francisco's Mount Sutro Forest, an oasis in the middle of the city, Plevin took more than a dozen nature lovers, mostly millennials who joined her online Meetup group, on a two-hour winding walk through towering eucalyptus trees planted more than a century ago.
"I spend a lot of time at my desk and not a lot of time in nature," said Daniel Sherman, a 28-year-old public relations executive with a San Francisco design firm. "We never stop to look at the leaves and feel the trees. I've lived in the city for 10 years, and I've probably never done that."
The thing about forest bathing is it's not a hike. You don't wear a Fitbit or chart your progress on your phone.
"The practice of forest bathing is about non-efforting," Plevin said. "So we don't have a destination. It's all about moving slow -- a lot slower than you expect.
"It's about engaging your senses, so when all of your five senses are engaged, you are by definition present, not lost in (your) head."
Plevin asked her fellow bathers to turn off their phones and put them away.
We formed a circle at the head of the trail, and -- as in a yoga class -- Plevin asked us to calm our minds, become more present, and deeply inhale and exhale. As we reached toward the sky, 100-foot-tall trees stretched dramatically overhead.
For the first 15 minutes, Plevin had our group walk in complete silence.
"Pretend that you've just landed on planet Earth, and you've never seen any of this before," she told us. "So, what's that smell like? What's that feel like?"
I immediately felt the "weight" of the forest like a blanket of green protection. As we walked slowly around the dirt path, light filtered through the towering old trees, dropping light patterns on the forest floor. Orange flower blooms so saturated with color seeped through my eyes and imprinted on my brain.
I felt better right away. Enter the sweet, playful sounds of hummingbirds, so many of them zipping like tiny helicopters at least 50 feet up to a treetop, then back down to a flowering bush. One hovered just feet from my face, at eye level. My heart raced from the pure joy of it. I felt a real connection.
"Gosh, it's really beautiful here. You can smell the eucalyptus and the flowers. You can see the berries are just starting to come out," gushed Maggie Collins, a 46-year-old project manager in San Francisco.
"There's something about being back outside. It's clearly ingrained in our DNA," said Sam Lazarus, a 30-year-old philanthropic entrepreneur and a Forest Bathing Club member. "For so much of our lives -- generations and generations have lived outside. It's only recently that we've spent so much of our time inside."
Throughout the walk, Plevin stopped at "activation points," where she invited our crew to smell -- and even taste -- the flowers.
"What do you think, peppery?" she asked. With assurances this had been done before without anyone keeling over, I tasted a petal. It was that brilliant orange flower, and yes, it was peppery like an orange bell pepper with a kick.
Later, Plevin asked the group to pick up a leaf and to think of something that makes us feel anxious or stressed -- and then to literally let the leaf go.
"So often, we're not even totally aware of those things that are, you know, running in the background of our lives," she said.
Later, our guide asked the group to stop and touch the bark of the trees -- and even to silently ask the tree a question to see what thoughts it might spark.
It was an unusual concept, Lazarus acknowledged.
"I grew up in the corporate world, grew up in Washington, D.C.," he said, "would never think I'd ever be talking to trees."
"Today, I asked the trees just about a little anxiety that I'm feeling around certain things in my life," Lazarus said. "And I realized the tree immediately responded with, 'We got your back,' and it was something that existed completely outside of my head. It's hard to put into words, right?"
Throughout history, humans and our ancestors spent every second outdoors in the natural environment, according to a National Institutes of Health study. We're talking 6 million years.
It's only with urbanization over the past couple of centuries that human environments changed drastically. And that means we need to make an effort to get outdoors.
"Really, what we should be talking about is: How are we doing without nature in our lives every day?" said Razani, the pediatrician.
In what's believed to be a first-of-its-kind partnership, Razani brought the East Bay Regional Park District together with her employer, UCSF Benioff Children's Hospital Oakland, to form a "park prescription and nature shuttle" program. She and her staff ferry patients into the parks.
"The impact on patients has been phenomenal," she said. "Many children spend 23 out of 24 hours inside. I don't think there's any animal that we do that to, even in captivity. I mean, it's not OK.
"The rise of indoor living has paralleled the rise of sedentary living, which has also paralleled the rise in chronic illness," Razani said. "So, one out of three Americans has a chronic illness. The rates of obesity and depression and anxiety are way higher in children, in particular, than they should be."
"The reason why chronic illness is so heartbreaking for the medical profession, and actually for parents, is because it's completely preventable," she said.
In 2016, Razani founded the Center for Nature and Health, which conducts research and offers medical care "in nature." Besides physical improvements, patients report emotional benefits, including feeling less anger, aggression and stress -- and more happiness, Razani said.
Razani recommends that her patients -- everyone, really -- spend at least one hour outside three times a week. But she prefers that we all get at least a small "daily dose" of nature, even just 10 or 15 minutes spent absorbing the green. And it doesn't have to be in a forest.
"You should step out of doors, and you should put away your electronics and look up and find what's alive," she said. "Whether it's the sky or ants on the ground or your child. Just take some time to be with things that are living."
Public entities and citizens also need to push for more parks and to preserve natural landscapes in the name of public health, she said.
As for the forest bathers, they emerged from their wandering fresh-faced and ready to take on the week ahead.
I'll be doing this again. Happily, I discovered a "shinrin-yoku" forest-bathers group near my home in Atlanta, and fall is just around the corner.
My fellow bather Collins said she could feel the change.
"I started out carrying, sort of, the outside world in with me -- like, the stress from work. And then progressively walking through the forest, I just was able to let go of that and take in more of the beautiful flowers, the sunlight and the sounds of the birds," she said.
"I could feel my shoulders lower," Collins said. "My mind just kind of relaxed into being right here."