India has a fast-growing medical tourism sector of its health care economy, offering low-cost health services and long-term care.[256][257] In October 2015, the medical tourism sector was estimated to be worth US$3 billion. It is projected to grow to $7–8 billion by 2020.[258] In 2014, 184,298 foreign patients traveled to India to seek medical treatment.[259]
Purchasing a rental property is another common way that individual generate an income stream.  It is very similar to investing, in that you take a sum of money to purchase the property, and the property returns a cash flow – rent.  You do have expenses related to this that are different from investing, such as a mortgage, utilities, property taxes, etc, which all must be taken into consideration when calculating a return on rental property.

P2P lending started in San Francisco with Lending Club in mid-2000. The idea of peer-to-peer lending is to disintermediate banks and help denied borrowers get loans at potentially lower rates compared to the rates of larger financial institutions. What was once a very nascent industry has now grown into a multi-billion dollar business with full regulation.
Portfolio income can come from multiple sources – interest/bond coupons, stock dividends, financial strategies including derivatives and capital growth.  Each offers some cash flow and some also offer potential capital gain with some risk from liquidity and volatile prices.  In this low-yield environment, many investors rely too heavily on cash flows and to pursue this are venturing further into riskier areas than they’d normally consider.