Too many writers are "serial starters". They begin a project, never finish it, let it stagnate, and then decide to start another project. This is definitely a bad habit and one we should grow out of. We usually think the way to fix it is to move on and finish your next project. But how about going back and finishing your old ones?
An unfinished story is like a loose end, begging to be tied up. Moving on to another project, whether or not you finish it, still leaves a project unfinished in your records. Completing your existing story can allow you to move on totally because you will have nothing to look back on.
You may be thinking that you don't like those old stories, so what's the point? The point is that if you have trouble finishing, the best practice is to finish. So go and do that. Nobody says you have to get those old stories perfect and published. You just need to get them finished. If you can do that, you will always be ready for your next project and you will always be able to give it your full attention because nothing else will be there to ask of it (at least as far as your writing projects goes).