The other point is that it is pretty easy to get started.  You don’t need to be super rich, and you don’t need a lot of time to get started.  To say it requires no time would be a lie, but you don’t need to make anything listed above your life.  You can work at your job, invest your excess income, save to buy a rental property or rent out a room in your current house, and you start a side job online without breaking a sweat.
What I’m doing: My realistic goal is to have a blended annual return of 2x the risk free rate. With a current 5% hurdle, I am not paying down mortgages that cost less than 4%. Debt at 5% is a wash. My realistic blue sky scenario is a 3-4X rate of return over the risk free rate which can be achieved with property, stocks so far for the past five years, and certain private equity investments. Where I am dragging is my blended average CD interest rate of roughly 3% from an old CD coming due. I’ve rolled some money into a 12-month CD with CIT Bank at 2.5%. It’s the best rate I can find. 
Venture Debt – I invested $120,000 in my business school friend’s venture debt fund. He started his own after spending 8 years at one of the largest venture debt funds as a Managing Partner. I’m very focused on income generating assets in this low interest rate environment. The true returns are yet to be seen, as the fund has a 5-7 year life before it returns all its capital.
Most employees will not see much income from social capital. While there may be the occasional gift or inheritance, Social Security and defined benefit pensions only begin to pay monthly income after retirement. On the other hand, those of us with medical and/or disability conditions may see income from matching social or insurance programs prior to retirement.
Investment in real estate can also be a source of a second income. If you have a decent sum of money lying around, you can use it to invest it to buy your second home. You may even take a home loan to finance your second home. This can become a source of income for you when you rent it to someone. These monthly rents would become your secondary monthly income. The key to making more money with rental properties lies in buying smart. Not all kind of property is going to give you a good return. Hence, analyzing the potential real estate opportunities is very important. The monthly rent highly depends on the area/location of the property hence it is highly important that you select the location of your property very wisely, keeping in mind the rent factor. You can save much even after your home loan EMIs. In addition to this, you can also avail tax exemption on the purchase of your property if it is through a home loan.
2. Focus on income-producing assets. Internet growth stocks may be sexy, but they provide no income. To build a large enough passive-income stream to survive, you must invest in dividend-generating stocks, certificates of deposit, municipal bonds, government Treasury bonds, corporate bonds, and real estate. You're free to invest in non-income-producing assets for capital appreciation too. You just want to earn reliable income when the day comes to leave your job.
I have several streams, which is really nice because you never know when one will dry up. I think I will be losing one of my contract optometry positions later this year. It sucks because I like the job, but it won’t be financial ruin. Even if you have a secure job, the side income does allow you to meet goals faster. I don’t think I’d ever go back to relying on one job, even if it was awesome.
Retirees are paying a high price as the world stimulates its way out of the GFC (Great Recession).  After a 30-year bull market to the lowest interest rates the world has ever seen, bonds have become highly priced and now don’t generate enough to meet income needs.  Just 5 years ago the average income from $100,000 invested in a 10 year Australian Government Bond (10yrs) was $5,600 p.a.  – now it’s less than half at $2,600 p.a.