/lit/ - Literature

How do I keep myself on track with only one project? I have a non fiction book on numismatics I've been working on for about a year, with maybe only a single chapter properly finished, a film script, and a few other projects I want to get done. But they all keep interrupting each other. Realistically I could have had my book published by now if I wasn't busy consistently flip flopping between my other projects and it. And I realistically could finish it in about a month considering much of the written sections are half/near finished. With only the cataloguing work needing to be done up from scratch (basically just a lot of spreadsheets and image scanning). Do you guys have any tips for keeping myself focused on one project and one project alone?