Maybe failure at something really hard wouldn't be so bad. I saw a movie once about a bike race north-south along the continental divide. Most who started quit at some point, but they didn't seem like failures to me.

Anyway, good luck. I bet you won't know what you want to do with your time until you've had some time to decompress first, so maybe just start with no plan.

It looks to me you really have issues with failure. I think you should address them.

For example, this advice tells you to do something out of reach. So you will have no chance in succeeding and failure will be to be expected. And so what? What is the problem with that?

The point here is not winning. So I second the advice and tell you to do it. You need to fail and overcome your fears seeing that it's not that big deal. You have to free yourself from the burden of fear of failure.

Have you considered that doing something scary might be a good thing?

You know what else is scary? Waking up in a country where you don't know if you're going to live or not that day. Count your blessings and see the world.