The wind is light today, taking a lazy brush over the teal surface of the lake. I step one foot into the water, then the other foot, bracing myself for impact. I put my arms over my head and dive, surfacing beyond the buoy line of the sandy beach. The waves are bigger the deeper I go, and occasionally I get a smack in the face and a mouthful of refreshing lake tang.

Soon I’m in the center of the lake, alone with the water striders, which scoot away from me on their long and spindly legs as my hands cut through the surface of the water.

My breathing settles and my thoughts fall away as I focus on the movement of my legs and arms, propelling me forward. The sun strains to break through the marshmallow clouds, its weak rays reflecting off the surface of the water.

If there is anything as peaceful as this, I have yet to discover it.

Dr. Melissa Lem, a Vancouver family physician and longtime advocate of the health benefits of nature, remembers feeling that same quieting effect while spending time outdoors. (Lem and I went to high school together.)

“I grew up feeling that connection to nature and not necessarily feeling as connected to my community as I should have been,” she tells me. She experienced racism and bullying on the playground and at school. “I found when I spent time at the park or when our family would go camping in Bruce Peninsula National Park . . . I felt so comfortable. I didn’t feel like anyone was going to come and yell something at me or exclude me.”

Lem tells me about facing other stressors in her early career as a doctor, and the way nature improved her mental health. In her first role, as a rural family physician in Northern British Columbia, she faced intensive work running an emergency room and performing acute care during long overnight shifts. Despite the challenges, she loved the work and credits easy access to nature as part of what helped her cope.

“My commute was walking to work past the hospital garden and looking at the mist rising over the mountains—I think that went a long way,” she says. Then she moved to the busy metropolis of Toronto, which she describes as “streetcar town, skyscrapers, and concrete.”

Suddenly she found herself much more stressed, even though her work was easier than in B.C. After she realized that her problem was a lack of access to the great outdoors, she decided to do a literature review to collect evidence that would support her intuitive sense that nature was a missing piece of the well-being puzzle.

“It had to be backed up by evidence, because I’m a doctor trained in evidence-based medicine,” she says. What Lem found was a large body of literature on the health benefits of nature, which she says none of her colleagues were talking about at the time.

A systematic review from 2018 included 143 studies on the topic from the previous decade, illustrating a recent and rapid growth in the study of nature and health. A quick search on PubMed for citations since 2018 gave me more than 2,000 results for “greenspace and health,” with that number growing year over year.

It’s not just the wilds of the forest that have been studied. The systematic review I reference above included studies of 11 different types of greenspace, such as urban trees and street greenery, larger parks, forests, and even the effect of viewing trees from a hospital room window.

The review found statistically significant benefits for a heap of objective (and some self-reported) health measures, including all-cause mortality, type 2 diabetes, measures of cardiovascular health, blood pressure, stress hormone levels, and preterm birth.

There are also many studies showing that nature can be therapeutic for those with mental health challenges, including reviews on horticulture therapy and wilderness adventure therapy for young people. What we don’t yet fully understand are the underlying reasons why greenspace might benefit our mental well-being, which means we don’t know enough about how to replicate these interventions for different populations.

Would gardening be something teens would want to do? Could wilderness adventure therapy work for older people with physical limitations?

“A doctor prescribing nature time in Regent Park is different from a doctor prescribing nature in Kitsilano, so we have to definitely be aware of our patient’s strengths and abilities, and also the communities we live in,” says Lem, comparing a low-income housing community in Toronto with a trendy neighborhood in Vancouver surrounded by beautiful biodiversity.

Lack of access to nature is a problem, with many people living in urban gray areas where scraggly trees barely survive in a concrete desert. “We’re coming up with a plan for programs where people can get free or discounted transit to greenspaces to reduce that barrier,” she says, adding that it’s also important to change people’s perceptions of what nature can be. “You don’t have to be in the middle of a forest by yourself or on the side of a mountain; it can be in your garden or your neighborhood park.”

It was a naturopathic doctor (ND) who handed me my first PaRx—a park prescription, sometimes called a ParkRx or NatureRx. I had exhausted all the treatment options with my family doctor and had turned to alternative medicine for answers.

In addition to several nutritional supplements and dietary changes, my ND suggested I leave my claustrophobic cubicle each day at lunchtime, head over to a small butterfly garden adjacent to our office building, and take off my shoes. I was to stand in the grass for 10 minutes, feeling the cool blades tickling my toes. This was written down on an actual prescription pad, and I carried the slip home with me in my bag.

The prescription felt silly at first, but I dutifully followed it every day throughout that summer. I would burst out of the air-conditioned building at lunchtime into a wave of oppressive heat, my eyes adjusting from fake fluorescent lighting to the stunning white glare of the sun. I’d shuffle around in the grass while other employees lounged near the garden eating their lunch.

And I was surprised to find that it helped—my lunchtime communion with this small greenspace seemed to set the tone for a better mood in the afternoon and post-work evening. I began to look for other ways to incorporate the outdoors into my everyday life, like biking to work instead of taking the bus. I went for daily walks in the ravine behind my house.

Nature prescriptions, or “nature pills,” are a growing area of interest for researchers and medical practitioners. Lem is one of the leaders in the movement in Canada and has launched the Park Prescriptions (PaRx) initiative with the BC Parks Foundation, a program offering health care professionals nature prescription files and codes, with instructions for how to prescribe and log their nature prescriptions.

“There are just under 100,000 physicians in Canada, and over 5,000 registered for our program, so that’s over 5 percent of doctors,” she says. “I think it’s important for nature to become routine advice during a health care visit—diet, exercise, sleep, and nature time.” Lem calls these the four central pillars of health, and she’s excited to see the movement growing among physicians.

I connect my own time in nature to similar benefits I get from practicing mindfulness. I believe that it’s not just about the trees that I’m seeing or the cold water that’s lapping around me. The setting becomes the doorway to a deeper connection with my body, which gives me the space I need to mindfully observe all the things happening within and around me—something I wouldn’t be able to tap into if I were distracted by my phone or hurrying through a park to get to a destination.

The science agrees with me: the mindful component of time in the outdoors could be one of the key reasons we experience such significant changes in our psychological and physiological health.

Other research suggests that it’s not only the positive health outcome that we get from nature that is the interesting part—it’s what predicts those positive changes. In the example of my cold lake swim, being in the presence of something awe-inspiring could be what’s causing real physical changes in my body.