Article writing is one of those things that isn’t at all glamorous, and few people will get excited about it.  With that said, it’s one of the easiest ways to set up your passive income stream.  To give you some perspective, I wrote about 120 articles late last year and have hardly written any since then.  Since that time, my articles have earned me over $700.   I continue to earn $70-90/month without having to do any additional work, which is something I look forward to every month.
This would only require the investment of your time. Start with a blog on something you love. It could be anything. From a travel blog containing pictures of your travels to a sports blog dedicated to your favorite team/sport. You can blog about anything and everything. It doesn't matter. But write regularly! I've read that an online magazine editor would personally prefer someone who posts something daily over someone who writes long posts once or twice a week.
Part of providing value is building trust. Don’t link to things that aren’t of good quality or people won’t trust your recommendations. The other part of making an audience is consistency. It matters less how often you post than how consistently. If you only have time to do one post a month, that post should come out on the same date and time each month.
Perhaps a coworker purposefully tries to make your life miserable because they resent your success. Maybe you get passed over for a promotion and a raise because you weren’t vocal enough about your abilities, and mistakenly thought you worked in a meritocracy. Or maybe you have a new boss who decides to clean house and hire her own people. Whatever the case may be, you will eventually tire.
First of all, let's face the facts. Working 9 to 6, you won't have any time during the day. If you choose to have a second job during the evening hours, you'd get burnt out very easily. Chances are that you might under-perform in both the jobs. I recommend having a side business rather than a second job. Some investment of money and time would be required at first. I have come up with a few options that would require less work from you but would be a decent second source of income.
One of the things I'm surprised your article doesn't mention is the tax advantages of this type of investment. The depreciation and rehab costs (purchasing distressed properties) can be huge deductions to ones income taxes, which none of the others have. Then, along with the appreciation of real estate, this passive income investment outperforms the notion of maxing out my 401k as well.
We have decided to invest in 2 ETFs, a multi asset allocation ETF (Fixed Inc, alts and div paying equities) and a preferred stock ETF. This will cover almost 45 percent of our deficit. We will be extremely diversified, can access the markets at a very low cost and the investments are liquid. On this pool of $, we have no plans to invade principal unless the investment grows by 20 percent, which we think is unlikely given the characteristics of the investments.
Several economic historians have argued that real wage decline occurred in the early 19th century, or possibly beginning in the very late 18th century, largely as a result of British imperialism. Economic historian Prasannan Parthasarathi presented earnings data which showed real wages and living standards in 18th century Bengal and Mysore being higher than in Britain, which in turn had the highest living standards in Europe.[101][78] Mysore's average per-capita income was five times higher than subsistence level,[115] i.e. five times higher than $400 (1990 international dollars),[116] or $2,000 per capita. In comparison, the highest national per-capita incomes in 1820 were $1,838 for the Netherlands and $1,706 for Britain.[117] It has also been argued that India went through a period of deindustrialization in the latter half of the 18th century as an indirect outcome of the collapse of the Mughal Empire.[78]

None legally required, but 7-21 days is standard for most employers. Typically, 10 working days. Many U.S. companies give only one week, and then frequently only after completion of a year of employment [e]. A recent United Nations survey indicates the average number of vacation days actually taken to be of 13 per year [f]. This corresponds to the fewest vacation days amongst advanced economies.

From 2000 to 2010, the country attracted $178 billion as FDI.[307] The inordinately high investment from Mauritius is due to routing of international funds through the country given significant tax advantages – double taxation is avoided due to a tax treaty between India and Mauritius, and Mauritius is a capital gains tax haven, effectively creating a zero-taxation FDI channel.[308] FDI accounted for 2.1% of India's GDP in 2015.[11]
Thirst for income is likely to continue with interest rates expected to stay low, keeping government bond yields low for longer and their valuations unattractive.  Looking past bonds, the prices of high-dividend shares are historically high, which limits the likelihood that their dividends will rise markedly from here.  Striving too high for an income target tends to push your portfolio further out on the risk spectrum.