If you have a spare bedroom, you can find a roommate or list the space on AirBnB for travelers. Having a roommate is the more passive of the two, as being an Airbnb host will require more work in the form of turning over the room between stays. This is a super painless way to earn $500 to $1,000 a month without much effort – you may even be able to cover your mortgage payment with this extra income!
If you are good at some subject, especially maths, science subjects, accounts or economics, you will have an upper hand in this business. There are plenty of such coaching centers so you will have to face some stiff competition in the beginning. But if you can get good results from your students, congratulations! You have made yourself a name and now parents will send their children in big groups to your center.

If you ask most people, social capital may not feel as strong or secure as it once did. Many people, especially younger people, do not expect to see a positive return on their Social Security contributions. Some do not expect to see anything at all from the Social Security Administration. The demographics of the system have changed from a past where many workers supported few retirees to a near future where existing workers cannot support the many retirees.
Estimated GDP per capita of India and United Kingdom during 1700–1950 in 1990 US$ according to Maddison.[97] However, Maddison's estimates for 18th-century India have been criticized as gross underestimates,[98] Bairoch estimates India had a higher GDP per capita in the 18th century,[99][100] and Parthasarathi's findings show higher real wages in 18th-century Bengal and Mysore.[101][78] But there is consensus that India's per capita GDP and income stagnated during the colonial era, starting in the late 18th century.[102]
4. Calculate how much passive income you need. It's important to have a passive-income goal — otherwise, it's very easy to lose motivation. A good goal is to try to generate enough passive income to cover basic living expenses such as food, shelter, transportation, and clothing. If your annual expense number is $30,000, divide that figure by your expected rate of return to see how much capital you need to save. Unfortunately, you've got to then multiply the capital amount by 1.25 to 1.5 to account for taxes.
To these human costs can be added the massive economic waste associated with the water and sanitation deficit.… The costs associated with health spending, productivity losses and labour diversions … are greatest in some of the poorest countries. Sub-Saharan Africa loses about 5% of GDP, or some $28.4 billion annually, a figure that exceeds total aid flows and debt relief to the region in 2003.Source 10
3) Create A Plan. Mark Spitz once said, “If you fail to prepare, you’re prepared to fail.” You must create a system where you are saving X amount of money every month, investing Y amount every month, and working on Z project until completion. Things will be slow going at first, but once you save a little bit of money you will start to build momentum. Eventually you will find synergies between your work, your hobbies, and your skills which will translate into viable income streams.
One of the benefits of the time we live in is all the software and technology we have available. If you want to scale a business that’s bigger than yourself, you’re going to need systems in place to get you there. These systems should involve automating as much as you can. The less involvement of you in the day-to-day means you have time to focus on the big picture strategies that help your business grow. 
You can provide tuitions to many school or college going students if you are good in a particular subject. Teaching students is also a great way to earn money. This way you can also enhance your knowledge about the subject you were passionate about. You can also go online and register yourself at websites and portals. This way you can maximize your reach.
While it is important to find something that you love to do and turn it into a money making business, you do have to be cognizant of the return as you pointed out. There are many opportunities that I found and tried out that at the time seemed great. But when I took a step back, I realized that I was working a lot for very little income whereas other things I love doing brought in much more money.
We encourage a more holistic, total return approach to your sustainable spending needs from investments.  An improved portfolio includes a wide range of income sources providing both cash flow and capital growth.  Your chosen blend should match your overall financial goals, considering your tolerance for risk, time frames, income and liquidity needs with a spending rate that sustains the investor’s wealth.