(CNN) Fall is a time when millions of birds will pass through our cities and towns on their trek south for the winter - known as Fall migration.
For me, the excitement about birds is year-round. Few things pull me out of a funk like the sudden appearance of a bluebird in my backyard, the vivid blue against a green magnolia tree like an exclamation point.
I scramble for binoculars to get a closer look, and as I turn the focus wheel, my cloudy, scattered mind refocuses too. The tiny indigo beauty rewards me with a chest puff, a rust-colored breast popping against the brilliant blue.
The sound of bird song and rustling leaves lead me to take a deep sip of fresh air, and the tightness in my chest disappears. My spirits, low since my mother's death, lift for now. I look skyward for the next flutter.
When you're birding, "you're almost in a different world," said Heather Wolf, a bird guide for NYC Audubon in New York.
It's a skill of fine-tuned observation, which rewards the birder with a new perspective.
"All of the things that might be weighing you down in your daily life, it's an escape. You forget about them when you're birding," Wolf said.
Wolf leads a group through Brooklyn Bridge Park, a mini birding oasis, complete with a stunning backdrop.
She takes the binocular-wearing birders through a paved path surrounded by foliage. You can hear the tweeting as birds dash between bushes or hop up tree trunks.
Wolf excitedly points out species along the walk: "A phoebe just landed." "Oh wow!! that's a woodpecker. It's a downy woodpecker. Everyone see that?"
Her excitement is infectious. There are more than 900 species of birds in the U.S. and Canada. Many of the birders on this walk are in their 30s, as birding increasingly draws a younger crowd.
While 45 million Americans say they regularly observe birds, according to a US Fish and Wildlife survey, Audubon's research found that 9 million of them are between the ages of 18 and 35.
Cameron Shore, a 30-year-old architect, says he finds birding to be meditative -- better than even yoga -- because it's outside in nature.
"Just being able to move around and pick out a particular sound or a particular thing to watch, I find it to be more focusing than anything else," he said.
"I actually have a lot of difficulty calming down in the city, with all the background noise and just everything that's going on. It's a nice time to come out and spend an hour or two kind of in silence."
Eric Hazeltine, a software program manager living in Brooklyn, is on the walk with his pregnant wife.
"You really have to use all of your senses when you do it," he said. "You can't even be listening to music or listening to podcasts. You have to keep your ears open and your eyes open."
A study from the University of Exeter in England found that people living in neighborhoods with more birds and tree cover are less likely to have depression, anxiety and stress.
The study, published in the journal BioScience, surveyed more than 270 people from towns throughout southern England. Researchers found a positive association between the number of birds and trees in a neighborhood and residents' mental health, even after controlling for a neighborhood's poverty level and other demographic factors.
The study's author says the need for more exposure to nature comes at a time of unprecedented biodiversity loss, which includes more than 300 threatened bird species in North America alone.
Another study in the Journal of Environmental Psychology found that just listening to bird song contributes to perceived attention restoration and stress recovery.
And beyond birds, there are hundreds of studies that show the health benefits of sustained exposure to nature, according to Dr. Nooshin Razani, a pediatrician and director of the Center for Nature and Health at UCSF's Children's Hospital.
"Within minutes of being in a natural setting things like cortisol, a stress hormone, improve," Razani said.
"Within 15 minutes, the ability to solve puzzles and cognitive benefits are seen. Even attention seems to get better. At around that time, blood pressure improves and so does pulse."
Razani notes that a lifetime of regular exposure to nature -- whether walking in a park or camping in a forest -- is associated with improvements in cardiovascular disease and longevity.
Then there are the health benefits of birding in a group, since multiple studies show that social connections and friendships are key to a long, healthy life. Sharing a hobby you're passionate about can connect you to others.
"A lot of times, when you're birding, you'll notice someone else with binoculars, and you can make new friends that way," Wolf said.
And there's a huge birding community awaiting you.
"I follow a few people's blogs and Instagram to see what birds they're seeing," said Amanda Warco, a 33-year-old Brooklyn educator who goes birding with her husband. "I like that it is a community and it's another way to get to know people who live around me that I probably wouldn't have any other interaction with."
You don't have to take a trip to Costa Rica to go birding. You can do it in your own backyard. In fact, backyard birders are the largest group of wildlife watchers in the country; 39 million Americans do it that way.
Or you can explore your own city. Birding can take you to new neighborhoods.
"I really would encourage anyone to just take a closer look at the trees in your neighborhood, especially around fall and spring," Wolf said.
Brie Stotler, a 39-year-old physician, hopes that as more Americans develop an interest in birdwatching, they'll become more concerned about the environment.
"Caring about the birds, you naturally start to think ... 'Well, do they have things to eat? Do they have a place to go?' And then that takes your thoughts to, 'What kind of parks do I have in the city?' or 'Are we preserving their natural habitat where they go to breed?' "
My bird habit started with observing flashes of blue, red and yellow through my sunroom windows. My partner bought me some binoculars, and my interest grew.
I was surprised to see so many colors and types of birds visiting every day. I ran to my bird guides to learn their names and match the pictures with my observations. Now, I know many of them by heart: robins, blue jays, Carolina wrens, titmouses, phoebes and my favorites, the tiny warblers, all 4 inches of them.
They flit so fast from branch to branch, often showing flashes of yellow, that it takes all my focus to capture them in my sights. This pulls into the moment, face to face with nature. Each bird has a sweetness, and their behavior becomes familiar and reassuring.
Now, I photograph them, too.
Recently, a surprise visit from a red-tailed hawk, whose soaring wingspan threw a shadow over my yard, drew me out of the house with binoculars to look skyward. His majestic soaring across the clouds lifted my spirit once again.