Music playing? Like guitar, ukulele, keyboard, harmonica

Or arts and craft, like watercolor, knitting, etc

I like to sit around and tie knots. It keeps my hands busy and I feel like it's something that could actually be of use too. First Class Amateur on YouTube is a great way to start.

Ropes, strings, cords, whatever you want to call it, can all be found just about anywhere and are pretty inexpensive

There is also the wide world of weaving/braiding bracelets and things. Google Macrame and boondoggle knots

So about a year ago I was having issues with eye strain, turns out playing video games that have bright deserts with a high default gamma on an already bright display causes temporary problems. I had a hard time looking at a screen for about a month. So I decided to start playing over the board chess at the local club and still do. Great way to hang out with people without screens involved.

You can also make chess pieces, boards or whole sets and probably make some good bank if the work is good.

Cooking is fun and you can eat the results. Find a recipe or a dish you've always wanted to try that is a little hard for your current cooking level but not impossible and spend a fun afternoon , in my case making chocolate eclairs from scratch. Mine look like turds but taste amazing, can't wait to try again.

I recently got into making foam inserts for my board game collection. Startup cost is low, just need a flat surface to work on and some patience. After measuring, cutting and gluing for a few hours, waiting for a few more for things to dry, then finally being able to assemble everything so it all fits "just right" is incredibly satisfying!

I make tiny towns out of paper, and foam. Based on unfinished wood rounds and painted with craft paint. Very cheap but rewarding.

With the low cost, it’s low stress as even a failure only puts you out a few bucks.

Building Gaslands cars is similarly fun and cheap. Get some Hotwheels cars and glue junk to them to make Mad Max cars.

And for more free time outside. Hiking is cheap, and some sun (with sunscreen!) is good for you and your mood. Hat, water pack, cordless silicon earbuds and play something on your phone and walk. Seriously, sunlight is positive for helping with depression in a ton of ways.

Book binding.

I make my own hotsauces and chili salsa's. You can go crazy with recipes, while it can't really go wrong. I also give them to friends who love them.

A friend of mine makes his own ciders (apple or pear). Very cheap to make with minimal investment. Easy to learn, hard to master.

I've been looking into making cheese, which apparently is also easy to do, and only requires some special cloth so low investment too.

If you're not into food/drinks; my gf crochets and knits. She learned it from youtube, and can make some cool stuff!

Papercraft. You can print out templates and they can get pretty elaborate.

My wife started with crochet a year ago by getting a Woobles kit, and now she crochets all the time, so that's probably a good place to start.

You could also check out a community art closet if there's one near you and start with anything that happens to be available in there.

Origami is pretty fun and cheap, and can be taken to craft fairs I suppose. You can find guides pretty much anywhere, and you can start making cool-looking stuff right away without fancy materials.

You can use normal paper for the simpler stuff -- just cut it to square by folding it into a right triangle first and folding the little leftover on the one side and cutting it off (or ripping it carefully).

Thin paper helps for the more complicated pieces, and you can get cool-looking patterns... but it's totally not necessary to get started.

To avoid looking at tutorials on a screen and if money is an issue. If you've got basic things like pen and paper. Drawing/doodling is a great place to start. Doesn't matter if you don't think it's good, just experiment.

You could try things like writing (especially if you're struggling with mental health issues) whether that be a sort of diary or wiring a story that tries to explain your feelings/struggles. My therapist actually recommended this to me and I found it incredibly helpful, especially as someone who has always hated writing. You can tear it up afterwards as well.

Knitting/Crochet is probably a little more than expensive, especially getting the tools, but is really good for giving your brain a break and falling into a rhythm.

Gardening, sounds odd, but you could buy some seeds for very little and try growing some things. It'll be slow, but it will get you outside and it's been proven to help improve mental health.

Walking without music. Just focus on your senses and what your seeing. Can be a great way to get your mind free of anxieties and stresses.

Puzzles - it's an activity that will also keep you busy and also isn't too strenuous.

Wood carving/whittling

If all you want to do is sit in front of a screen, you'll have a hard time finding the motivation to stick with a hobby; you should start by thinking about things you already enjoy, and then figure out how you can turn those into hobbies. I'm not a motivated person at all, so most hobbies I've been interested in haven't panned out, but I love eating good food and hate spending money, so I'm motivated to bake and cook for myself, to the point where those became good hobbies for me. If you can't think of anything you like, then just try a bunch of things until you find something you really like.

Not sure what country you are in or your budget, but what about signing up for a evening course?

I started with pottery, 5 times a 2h. A couple of years later I had a permanent place in a proper studio.

Woodworking? Painting? Tufting? Modelmaking?

Macramé just requires string and knowing how to make some types of knots. No special instruments needed (although in actuality a clip to hold the string is very useful and others to hold parts if you get super complicated). Something interesting off the bat is a david and goliath type sling big enough to toss a tennis ball if you have a dog.

I really enjoy woodcarving and whittling. All you need is a knife and some wood! Look up Doug Linker on youtube fit some starter ideas. I made my whole family tiny santas for Christmas

I’ve become a big fan of knitting while watching movies. Two hours later I’ve seen a new movie and have made good progress on a hat!

I am pretty similar to you. I started looking around my home for things that need fixing, or could maybe be improved. I didn't really want to spend a lot on any of that, so I've redneck engineered a lot of things. Turns out I'm pretty good at it. Glue, string, cardboard, wire. Any scraps you have lying around can probably be used on something.

Crochet. Lot of things to make which are small so the hobby is very portable.

Quilling can be fun. You just need to cut thin strips of paper and shape it. It’s kinda easy if you have decent hand eye coordination. It can be easy to start if you have paper, scissors, and some glue laying around. It looks like 3D art and is beginning friendly.

Hiking, running or trailrunning

Lego my dude. Its expensive but endlessly reuseable.

I picked up Warhammer for the same reasons and have been loving it! I'm not into the gaming side, I just enjoy building the models and painting them.

Sewing and knitting. Also relaxing.

origami! all you need is a paper and infinite possibilities await you. you can go as simple and as complex as you want and they make great little random gifts for those around you

jo nakashima has some great and easy to understand tutorials if you are wondering where to start

I like doing cross stitch! It’s very simple and easy to get into since you can buy cheap kits that come with everything you need, it doesn’t have a steep learning curve and you get to enjoy the end result.

i like coloring books and dot-to-dots. books and crayons/coloring pencils are inexpensive and will keep you busy for a while

Making terrariums is a lot of fun and very addictive. A little self-sustaining ecosystem.

When I was a kid I used to make keychains using these:

Great Five 160 Scoubidou Strings Plastic Lacing Strings Craft Gimp Lacing Cord 16 Colours 10 strings per colour Craft Strings Bracelet Key Rings (160 meters) https://amzn.eu/d/g5BrI3U

They were all the rage in 1988. 😂

Bake cookies. It's really simple. Not overly time consuming. You get a tasty reward. You can gift them to neighbours and coworkers to make people happy.

I really enjoy woodcarving and whittling. All you need is a knife and some wood! Look up Doug Linker on youtube fit some starter ideas. I made my whole family tiny santas for Christmas

just run around (or speedwark if you're) house
or apartment (is tiny)