Nobody gets early FI investing in bonds, CD’s, or even stocks unless they make a huge income or are extremely frugal or a combination of both. Paper assets just don’t provide enough returns. Business income can be great but it is typically not as semi-passive as I would like and there is a relatively high failure rate. That is if you can monetize an ideal to begin with. RE investing needs to be higher ranked IMO as a way that the “average guy” can become FI.
Have you always wanted to own your own business? You could start a side business while you work a full-time or part-time job. For example, if you're a graphic or web designer, you could start your own graphic or web design business on the side. If you like to make jewelry, you could sell at craft fairs and online. Starting a business may be daunting, but if you believe in you and your work, you could earn a decent living, maybe even quit your day job. Search out those who are doing what you want to do and interview them. Find out the mistakes they made and ask for guidance.

But two months later, with the economy slowing down after the financial crisis, his firm began laying people off, and Flynn was informed that after his current projects were finished, he also would be out of a job. At the same time, he couldn’t help but notice that in the LEED exam forums he had frequented, people were referring to him as an expert and directing questions his way. He began to think he might capitalize on that.
Creating passive income is the key to retiring, especially retiring early. If you want to retire early with the stock market you will have to save a huge amount of money, because that money has to last so long and retirement calculators depend on you using your investment to fund your life. With passive income you will have income coming in as long as you own the investment, without every eating away at the principle invested. Creating passive income may take more work than investing in the stock market, but I think it is well worth the extra effort!