I enjoy doing outdoor activities like visiting parks, but it is a bit cold for that at the moment. A lot of indoor activities get pretty expensive, but I have in the past found a few free building tours and similar which are really good.
I’d love to hear about things everyone else enjoy doing that don’t cost too much, and any resources you use to find activities.
Most of my hobbies are ones that can be very expensive, but don’t have to be. I’ll start with a couple that I do this time of year even though they’re outdoors.
I’m big into running. Good running shoes can run you a lot of money, but you can get a pretty cheap entry-level pair and keep healthy without any ongoing cost. Save yourself that expensive gym membership. It’s hard to get out the door in winter, but once you do it’s a great experience because you don’t end up quite as drenched in sweat as you do in summer. As @Ilandar mentioned, Parkrun is available as a free race every week if you want to have a benchmark to test yourself against, or want a good social opportunity. It’s 7am in Qld though, not 8am. I know NSW is 8am, but outside of those two states I don’t know, so check your local races’ websites.
Photography. If you’re really into it you’ll probably eventually want a DSLR or interchangeable-lens mirrorless, plus some lenses, but you can do a lot of stuff with just your phone, if you already have a decent phone. Sports and wildlife photography will suffer the most without better gear, but landscapes, cityscapes, candids of people and a bunch of other styles rely much less on the technical capabilities of higher end gear, and proportionally more on just composition, which a phone can do equally well. (You just gotta git good.) You can rug up in your warmest clothes because there’s no need to be moving around very quickly most of the time (again, unless you do sports photography). Or you can explore creative ways of taking photos of things in your own house for a more deliberate artistic expression.
Since you were mainly asking about indoor activities, the obvious classic answer is video gaming. Yeah you can buy half a dozen new games every time there’s a Steam sale and run them on the latest and greatest hardware. But you don’t have to. I’ve pretty much only been playing 2 games over the last 4 years: Age of Empires 2 and Age of Empires 4. They run great on my computer which was a moderately powerful gaming PC when I built it in 2017. AoE is a great game because you can have a blast just messing and doing campaigns or beating the AI, or you can take it very hardcore serious on the 1v1 ranked ladder, or you can enjoy it with friends via the ranked team game ladder or by doing teams against the AI. I do all of these depending on my mood.
SA is 8 AM. I just (wrongly) assumed all of Australia would share the same start time. Seems northern States and Territories start earlier while southern ones start later (Tasmania is 9 AM).