While this is (probably obviously!) very subjective from author to author, I think "the character didn't want to do the thing I'd planned for them" is a good th

While this is (probably obviously!) very subjective from author to author, I think "the character didn't want to do the thing I'd planned for them" is a good thing story-wise, because it means you really understand your character. The flip side of that, though, is "the character didn't want to do the thing" isn't necessarily a sign that the character shouldn't do the thing. In general, your protagonist is going to have to be pushed out of their comfort zone during a story, and they are not going to like it. Frodo did not start out The Lord of the Rings thinking "throwing this ring into a volcano in Mordor sounds like a lovely few weeks' vacation."