Yes, I think I get your point.

"I'm confident" seems a good antonym of "I worry". I'm confident that turning on the tap is safe for humanity. I have reasonable expectations of getting water when I turn on the tap (though these are sometimes violated).

The tap example is reminiscent of the blue tentacle line in Technical Explanation. Riffing on that, beliefs perhaps correspond to scenarios you construct without really thinking about it, plausible extrapolations from actual knowledge.