My son is 7, but is a HUGE scaredy cat. He won't ride anything fast, or even remotely scary (Test Track is a no-no and Pirates is a maybe - yes with lots of coercion, for year he was terrified of the safari at ak). This last trip we were in AK, it was ridiculously hot and we needed to be inside. The restaurant wasn't open yet and the Dinosaur ride was literally the only thing with a/c. So we got in line, thinking he'd chicken out before we actually got on the ride.
A LOT of kids chickened out after the pre-ride video but my son said he'd go on it (reluctant but insistant). Surprisingly he made it through just fine. He said he never wants to do it again, but he liked it.
I did emphasize that it was all pre-tend and nothing bad was really happening (we were just in a big building, we didn't actually go back in time).