Making legitimate passive income isn’t as difficult as you might think. Some of the best passive income ideas might take a little time to set up but can start cash flowing within a couple of months and will provide a consistent monthly income for years or more. The most important point is just to get started. You make exactly $0 on the passive income sources you never start.
Investing in rental properties: Another form of real estate investment, rental investments (i.e. becoming a landlord) could steer you down the passive income path of steady monthly rent checks that you can use to pay off a mortgage loan on the rental property. After the mortgage is paid off, those monthly checks go right into your bank account -- potentially for years to come. 
Another benefit of residual income is that, if the income stream is large enough, one does not need the main focus of his life to be on making enough money to survive. Having a comfortable and continuous level of residual income opens up more opportunities to travel, look into other business opportunities, and even take the time to indulge in his hobbies.
Residual income is the amount of net income generated in excess of the minimum rate of return. Residual income concepts have been used in a number of contexts, including as a measurement of internal corporate performance whereby a company's management team evaluates the return generated relative to the company's minimum required return. Alternatively, in personal finance, residual income is the level of income that an individual has after the deduction of all personal debts and expenses have been paid.