Good discussion. Different income streams have different levels of work required. Buying a good rental property is hard work, but there isn't much to running it if you have a good management company. I have seven houses and spend just a couple hours per week keeping the books and maybe touching base on repairs or vacancies. Like you say, writing a book is hard work, but the income can continue after you are done unless you are doing the marketing yourself. Running a business is never passive unless you get it large enough to afford a strong CEO that can take over, which doesn't happen very often. Although there is no truly "passive" income, it does help to understand how active your chosen side-hustle is to know if it fits your current or desired lifestyle.