Incomes can be broadly classified into two categories, Active or Passive. Simply speaking active income is made when you work for money and passive income is made when your money works for you.
All the riches in the world are rich not due to active income but due to passive income because of one simple fact that you have limited time and strength to work for money but your money can work for you 24/7.
So if you really want to be rich, which I know you definitely want until and unless you have become Saint, start working from today itself towards building your assets that appreciates and generate money over time. For example Equities, Real Estate, Web assets such as blogs, videos, websites etc are assets that appreciate over time and also generate regular income.
Before you start building your passive income plan, one very important concept to understand is the difference between Assets and Liabilities and how to minimize the later and maximize the former. Robert Kiyosaki, the author of famous book "Rich Dad Poor Dad" has beautifully explained this concept in the following video at Assets vs. Liability
For more details about building your passive income check out the following ebook: Passive Income PDF