From my personal experience, it took me years of discipline to build up the skillset to finish a project. It took me years to be able to learn what I can do and what I can't do given a specific timeline and be able to set tangible and achievable goals and focus on that to complete them. (And tangentially, if you ever want to offload your side project, here's a place to submit if you like :) https://www.sideprojectors.com)