I can start a story, but can I finish one?

I came up with a story idea a couple of days ago, but when I went to try and write it out, I ran into the same problem I have been dealing with for a while - I get to a point, and I just run out of steam.

I have about a dozen stories in more or less the same condition, but I am wondering if this is why I favor flash fiction - one way to get around the sticking point is to just end the story.

I am not desperate enough to try AI, but I am not sure what I can do.