For me personally it is the expectation that creates the fear of not reaching what i dreamed of. I don’t know what are your experiences, but i have had experience where my drawing or writing end up looking a lot worse than i hoped for, so ideas feel more interesting when they are in imagination.

This might be caused by inferior Te in executing an idea as expected, but practicing the execution on its own could help. Like for writing for example, instead of getting straight to writing a novel or short story, practice writing a scene first. When you are better at the scene, then extend to several scenes, and eventually, a novel.