​Udemy is an online platform that lets its user take video courses on a wide array of subjects. Instead of being a consumer on Udemy you can instead be a producer, create your own video course, and allow users to purchase it. This is a fantastic option if you are highly knowledgeable in a specific subject matter. This can also be a great way to turn traditional tutoring into a passive income stream!

Thanks for asking. https://passiveincomemd.com/what-is-passive-income/ gives a good summary of the definition I use. But in brief, it’s income that isn’t proportional to the time you physically put into acquiring it. It doesn’t mean it’s not without work or effort. It’s just that most of the work is done up front and it continues to pay off long after that initial effort. Real estate fits into that box. There’s definitely a spectrum but compared to what we do as doctors, where our compensation is directly linked to our time, most of these things are quite passive.
The second category of passive income is drawing on sources that do not require capital to start, maintain, and grow. These are far better choices for those who want to start out on their own and build a fortune from nothing. They include assets you can create, such as a book, song, patent, trademark, Internet site, recurring commissions, or businesses that earn nearly infinite returns on equity such as a drop-ship e-commerce retailer that has little or no money tied up in operations but still turns a profit.
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.
3. Start as soon as possible. Building a livable passive-income stream takes a tremendously long time, largely because of declining interest rates since the late 1980s. Gone are the days of making a 5%-plus return on a short-term CD or savings account. Today, the best 12-month CD is at 2.5%, and the best money-market rate is about 1.85%, which is not bad, considering such rates were below 0.5% just a couple of years ago. Know that every $100 you save can generate at least $2.5 in passive income.
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What I did:The first two years of work in NYC was brutal. I told myself there was no way I could work on Wall St for my entire career because I’d probably die from heart failure by age 40. Having an early death in my mind willed me to save 50%+ from the first year onward and devise a CD, real estate, and stock investment distribution system for my savings every year. I thought about starting this site for at least a year before I hired someone from Craigslist to give set me up and push me forward. Hiring someone to get started is totally worth it if you are a master procrastinator. You can now learn how to start your own site with my step-by-step guide to save yourself time and money. 
The doctor or lawyer, for instance, could use her or his income to invest in a medical start-up or buy shares of medical companies he understands such as Johnson & Johnson. Over time, the nature of compounding, dollar cost averaging, and reinvesting dividends can result in her or his portfolio generating substantial passive income. The downside is that it can take decades to achieve enough to truly improve your standard of living. However, it is still the surest path to wealth based on the historical performance of business ownership and stocks.

Reality One: We live in a competitive and fast changing world. Business has become highly specialized and niched because knowledge is growing exponentially, requiring specialized skills to employ it properly. Successfully competing in many widely varying fields is contradictory to the specialization and complexity required by our current business climate.

You can select any of the above fields based on your skill sets to create second income source. There is no dearth of opportunities, only thing matter is to identify the right one, which suits you. There is no shortcut to success but you have to start journey from some point. Recession can push your career 5 years back but with proper planning you can minimize its impact and remember Bad Times also don’t last forever.

4) Treat Passive Income Like A Game. The only real way to begin your multiple passive income journey is when you are making active income. The initial funding has to come from somewhere. Hence, treat passive income as a game that has various levels. If you fail to achieve one level, it’s not the end of the world since you still have active income and can restart. Furthermore, a game is meant to be played with integrity. Using shortcuts (non passive income streams), someone else’s income as a supplement (spouse), or one-offs (capital gains) does not count. The primary purpose of any game is to bring enjoyment to the player and beat the boss.
Income-generating assets are another of many passive-income opportunities. A classic example is making money in real estate via owning rental properties. It can seem perfect: You buy an apartment building or house, rent it out, and then sit back and collect checks every month from your tenants. The reality isn't always so rosy, though. For one thing, you'll need to maintain and repair the property, as well as paying taxes on it and insuring it. It may not always be occupied, either. You may have trouble finding tenants, or finding tenants who pay their rent reliably. Some tenants may damage the property, and others may be hard to get rid of. You'll be the one they call in the middle of the night if the roof is leaking, and you'll have to clean and perhaps freshen up the property between tenants. You can outsource much of this to a property management company, but it will take a cut of your income, often about 10%.
In addition to opening a brokerage account, you can also invest in peer-to-peer lending firms like Lending Club. I’ve been using Lending Club for a few years, and my net annualized return was 6.02% percent last year. Picking the right investments is easy since the platform offers automatic investing, but you can also pick your own notes if you're brave and want to learn the best ways to leverage the Lending Club platform.