An important moment in my development as a writer was learning to think in scenes.
This is a good life skill too, being able to break things down into their constituent parts.
You’re not writing a book, you’re writing a chapter.
You’re not building a wall, you’re layering wet cement and placing one brick at a time.
For stories, the basic building blocks are the scenes. Just focus on one at a time.
This works because a scene has the same basic structure as a story, but on a smaller scale. Each scene has a beginning, middle and end. Further, each scene is somewhere along that the beginning-middle-end spectrum in the greater story.
Writing a story can be overwhelming. Writing a single scene is eminently manageable.
Break it down. Focus on one thing at a time. You’ll get there.