Investing in bonds: Similarly, bonds are an attractive way to engage in passive income. Over a recent 45-year period, bonds funds, as measured by Vanguard Funds, returned 7.1%. Of course, there's no guarantee that investments in stocks or bonds will always work out well, investing in them is by far the surest way to generate money through passive income.
I have a total of three CDs left. There is no way in hell I’m selling them after holding them for 4+ years so far to take the penalty. The CDs are for 7 years. That would be completely counterproductive. As a result, I feel very stuck with ever getting my CD money back if I wanted to. If the CDs were for just 1 or 2 years, I agree, it doesn’t matter as much. But combine a 7 year term with 4%+ interest is too painful to give up.
I would throw in some caution here: if your spouse works at the same company, or in the same industry as you, you are not diversified, and should something happen, you could be in a world of hurt.  Companies do go out of business, companies do lay employees off.  There is nothing wrong with working together, but realize that you are not diversified and you should be trying to maximize other income streams as a result.
In January 2018, I missed my chance of raising the rent on my new incoming tenants because it didn't come to mind until very late in the interview process. I didn't write about my previous tenant's sudden decision to move out in December 2017 after 1.5 years, because they provided a relatively seamless transition by introducing their longtime friends to replace them. I didn't miss a month of rent and didn't have to do any marketing, so I felt I'd just keep the rent the same.

Rental properties are defined as passive income with a couple of exceptions. If you’re a real estate professional, any rental income you’re making counts as active income. If you’re "self-renting," meaning that you own a space and are renting it out to a corporation or partnership where you conduct business, that does not constitute passive income unless that lease had been signed before 1988, in which case you’ve been grandfathered into having that income being defined as passive. According to the IRS, "it does not matter whether or not the use is under a lease, a service contract, or some other arrangement."
You can’t start charging right off the bat without your audience knowing anything about the value you offer (though you could still indirectly earn money from them with the right ads). “The best way to go in terms of a long-term passive income business [is] delivering value and information for free, and therefore establishing expertise, knowledge and trust with your audience,” says Flynn.

After employment, I think that most individuals gain income diversification through investing.  It is important to look at why we invest: because at some point we plan on using this money for something.  For most, it is saving for retirement, and the investing is done through vehicles, such as a 401(k) or IRA.  But investing is not just about stashing money away for a rainy day – that is what an emergency fund is for.  Investing is about having enough capital to generate income.
Increase in income Income per capita has been increasing steadily in almost every country.[5] Many factors contribute to people having a higher income such as education,[6] globalisation and favorable political circumstances such as economic freedom and peace. Increase in income also tends to lead to people choosing to work less hours. Developed countries (defined as countries with a "developed economy") have higher incomes as opposed to developing countries tending to have lower incomes.

If you’re worried about launching a new product, and think you might need some feedback to make it really good, Flynn recommends “pre-selling” an idea — for instance, offering a limited number of spots or seats into, say, a course you create and giving the test group specialized attention so you can see how to improve the content. Once it’s revised (or, if it’s software, once all the bugs are removed), you could open it up to your whole audience.
And, let’s face it; not everyone wants to sling body wraps or nutrition shakes to their family and friends. That’s why offering a service is often one of the best, and least uncomfortable, ways to earn side income doing something you love. Maybe you want to clean houses or rake leaves or help people file their taxes. It’s totally up to you, and that’s the beauty of this option.