I have seen a related question, but the answers don't seem to provide solutions, just notes that it is indeed a problem.
The Unfortunate Human Being (otherwise known as Main Character) must make a living in a world where there is no possibility of contact with any human being or intelligent alien.
He can bring animals or insects or a pet fish (if he has a leash). Recordings and manuals, books, etc can be taken. They can even take their house somehow. Anything is possible but communication with humans, including online, visually, smoke signals, etc.
They can set up a home or be on an island, on a mountaintop, or they can stay in constant movement. There's no external factor in their decisions, they're entirely self-motivated.
For some reason no matter where they go after they embark on this fun journey they will not find any sign of civilisation, nor another person to talk to. The period without other people may be years, even decades.
Our character knows they will be isolated. They're okay with that, but they know that being alone for an extended period makes people a bit off-kilter.
What's the recommendations for them so they can stay as sane as possible?
(I'm looking at psychology primarily, including indirect factors, e.g. injury increases odds of dementia, LSD gives you a lot of company, don't stay in the desert)