I define a project as something I do with an outcome I want. The problem is when I keep starting projects, then one day, I realize I have created dozens of projects. Every week the list grows longer.
Why do I create projects and not finish them? Because I don't know what done looks like. Each project becomes a giant neverending slog because I think of all the possible things I can and want to do as part of that project.
What's the solution? Before starting any project, define the scope of the project. What is and is not included in this particular project? If the scope starts growing, tell yourself these extra things can be the next project and keep this project small.
Why do I like this? Because I finish projects and finished projects are progress.
It also gives me natural breaking points. Instead of feeling like I have to work on the same project forever, I get to finish and re-prioritize before starting my next project.
That way, instead of a giant list of unfinished projects, you have a list of finished projects and a list of possible next projects.