Perfectionism is too positive a word for this (“my greatest weakness? I am a perfectionist.) Fear of failure feels more apt. I hesitate starting/taking the next action because I am not confident I can land the goal all the way. IE - I fear trying to do X and not nailing it more than I fear not even trying it in the first place.

Like many fears it is usually inappropriate and unhelpful. In reality you are almost always further ahead in life if you try even if you don’t get to the outcome you envisioned.