It's hard to know how much are inherent personality traits & how much is a response to Life, isn't it?
At 2 my niece barely spoke. As she got older & it became more obvious we paid more attention. One day I overheard her playing alone & reciting her abc's & chatting away very, very quietly. When she started talking she was all words one day & full sentences the next. She'd been secretly practicing & went from being the kid that never spoke to the kid that spoke well, practically overnight. She's always been careful, methodical. Her father is an alcoholic, she deals with abandonment issues, and at that age she'd been exposed to a lot of hidden fighting & abusive talk by him toward my sister... but there's no way I could connect the 2 in cause/effect. That would be insanely presumptuous.
I know that the fear part for me came down to separating what was legitimate fear/worthy of the stress & what wasn't worth getting worked up over. I guess I never really learned the difference as a kid & after so many years of everything signaling a full-fledged response, it was just habit to over-stress every little event. Or non-event, as it were. So, Lexie's example of travelling to a foreign country for the 1st time would definitely be worthy of stress for me & it would be hard to stop that from becoming compulsive overthinking in terms of safety, language, access to finances in emergencies. But it would be easier to let go the 2nd & 3rd times & a no-brainer the 4th. (in my rich, alter-life I guess, ha!)
Another wise thought that keeps me moving forward when I start to let fear creep in is, "The answer is always No when a question is never asked."... which I also equate to my choices/actions (not just words) in terms of my universal path. The door is always closed when I refuse to turn the knob to see if it's locked. I will always fail if I never find the guts to try. And since I have honestly learned something from every little failure, what's really at stake in most cases?