Volunteering really helps me feel more relaxed. I've helped out at churches, a food pantry and animal shelters (including at a vet clinic connected to one of the shelter groups).
@sun seeker, you said you lived in a rural area? If there are any ranches/farms with animals nearby, could you ask the farmers/ranchers to help out with the animals? Or around the farm in general?
Could you volunteer to tutor kids after school or help out in the cafeteria? My mom was a Teacher's Aide for like 10 years, and one of the extra duties they'd have her do is monitor kids at lunch and recess. She would have preferred to be in the classroom !
The library is another great place to volunteer. Outside of simply immersing yourself in the calm and peaceful atmosphere to help lessen your anxiety, you can ask if you can read to kids (or adults!), help organize books/movies, or even water the plants. On that note, any kind of bookstore can also serve as a place of peace. Normally, you can just hang-out/forever browse until you're ready to leave. But, if a clerk/manager is picky, just buy a cheap book/magazine on your way out :)
I hear gardening can also be very stress-relieving, though it seems to depend on what you choose to care for. I had a coworker who started growing various herbs and selling them to restaurants as a side-business. He really enjoyed caring for his "product" and learned a lot about it too!
I live in a city, so I guess I'm trying to think of things I would do if I had lots of space and a yard :P
Don't forget the always-and-forever popular listening to music suggestion! You can use a streaming source like Spotify for free to listen to lots of different genres of music. They even have many playlists that have nothing but soothing and relaxing tracks on them! Whatever you choose to listen to however you choose to listen to it, aim for positive, uplifting, and calming tunes. This can be anything that puts you in a good mood or even a trance/meditative-like state (if you want that!). Mind you, I listen to tons of different music, but I'll use a couple as broader examples of what I mean. I love techno and hard rock, and the artists I enjoy leave me feeling happy, pumped, and/or generally good about life and myself. Positive rap, Christian rap, Christian, and Gospel/Choir music are some examples of music intentionally created to leave you feeling calm, positive, and less-stressed. Music is so so powerful and can affect our moods a LOT. We can use this to our advantage :D
Looking up at the stars, taking a peaceful walk, doing anything where I'm really connecting to nature can *really* help me calm down when I'm feeling over-stressed.
Arts and crafts (or any other preferred hobby!) are great ways for me to become less anxious. I mainly cross-stitch, and that requires me to be focused on following the pattern plan, thinking about if I like one color floss over another, how to tie a French knot, etc. All takes my focus away from myself and my problems and onto something fun that relaxes me.
I think that's all I got for now, lol.
Hope it helps get some wheels turnin'!