Bushwalking options for solo travellers in Korea

I occasionally go bushwalking (hiking), and would like to do so in South Korea if possible.

The main concern I have is safety. I'm concerned about going bushwalking solo, because I have it ingrained in me that I shouldn't do so for safety reasons, such as snake bites. (I don't want to scare anyone off from bushwalking in Australia - so long as you take sensible precautions, it's reasonably safe) Wikivoyage's guide to safety in South Korea doesn't mention snakes, but it does mention hornets inter alia.

What options do I have for bushwalking in South Korea? For example, are there places that are so busy that another bushwalker would pass you every five minutes? Or are there companies/youth hostels that can organise non-overnight bushwalks? Or can I hire a tour guide inexpensively?

I'm not as fit as some people, so I suspect that if I join an existing group uninvited I might slow it down.

I don't know if coffee ladies (Bacchus Ladies but within bushwalking tracks) still exist, but if they are, they're not a concern, as they're not a threat to my safety.