If you want to make passive income then you should use the leverage of the Internet to make this a reality.  The idea is that you can create something of value, post it online, and get paid for that value over and over again. 

Making passive income is not difficult if you can figure out a way to provide this value in a permanent format.  Once you create one stream of income that is passive then you can duplicate your efforts in other areas as well.  The Internet is a big enough market for you to do this over and over again and keep getting paid.