Go for a run, leave your buds at home, report when you're back :)

I think I know how you feel. I love long solo runs/rides/hikes. I'd lie if I said I was never afraid of random thoughts popping into my head.

I look at it as sort of meditation. There're plenty of articles regarding fear of meditation. Check them out. You're not alone afraid of being alone.

I'm not afraid of random thoughts, nor being alone - I have a sense of unease about being a decent distance from home and not being entertained on the way back.

Let's not over diagnose this :)

I was talking specifically about the unease of not being entertained, thus forced to be with yourself.

Just sharing my experience. Unease usually doesn't come from nowhere. Everybody is different though.