Your island. That's right, it's your island. Nobody else is there. Maybe animals. Enough food and you, by this point have some situation for temporary living setup on this island already. You do not yet know the size of the island. You do not know the geography of the island yet or what else might be on the island. You are dependent on no one and no one is dependent on you. You are dependent on yourself and you are dependent on the Island. The island is independent from you, as is the rest of the world.
Now, of course, of course you have too too much time to think. Ask yourself these questions: Will you build first, or will you explore? Of course you'll explore, but how far will you explore? will you map out the island and pick the best spot to set up? Are you the kind of person that will even be concerned with where exactly you set up? What do you think you'll look like when your appearance is completely independent of the opinions of others? Do you think you'd be able to notice a difference in your mannerisms? Would you keep your voice in practice by talking to yourself or would you be concerned enough about stealth to keep quiet? Would you find a way to write and at least keep your penmanship even if you don't deem it necessary just to expel your built up thoughts?
Oh! Something new has happened.
You find a box of books. They're not your books. They're old, but the pages still turn. What books are they? Which one do you read first? How much of your time do you let yourself spend with these new books.
There could be someone there, couldn't there? Would they be someone you already know, or no? What would they look like? How old do you think they would be? What sort of relationship would you have with this person? Would they be a mentor, a nemesis, a guru, a lover? Would you be the kind of person to pick someone to have with you or would you let providence put someone there? If you did decide to bring someone, did you think of them as the lover? Do you think your friends would have made the same kind of choice?
Back to exploration. How much of the Island do you know by heart already? All types of geography are possible. Do you like the spot by the cave, or by the beach? On top of a hill or under the cover of trees? What do you do in the places you find? If you decide that there's someone with you, what do you do with them in the places you find? If you have someone with you, are the limitations on the things you might do in these places with them changed? Well, of course they are. Isn't it true that most of these limitations are dependent on the opinions of others? But aside from that, would something like an age difference still be as much of a limitation? An obvious difference in maturity would of course be a limit, but it's not always like that, is it? When with someone who is obviously mature beyond their years, are you affected by the difference in days experienced? What will you do for your mind? How easily do you think you could keep yourself feeling sane? What would you miss badly enough to mourn for? Anything? Well, how long do you expect it would take to set in? More importantly, how long would it take for you to regain your resilience?
Here's what I'd do to keep sane: Keep moving. Build shelters at different spots. Stay in the next place I don't know yet. I'm somewhere new. I'm always moving, learning. I don't let myself get too comfortable in one spot.
Remember this: Chaos teaches patience.
Please don't forget about the necessary Chaos.