It may sound like a daunting task, but it can be explained in a simple way. You have to satisfy a need that people have. Do people want a website that connects them to others with a similar interest? Do they want cheaper air fares? Do they want a personalized career path finder? You don’t have to create something new or ground-breaking; you can simply take existing services, and improve them in some way. Or you can create your own.
If you have a spare bedroom, you can find a roommate or list the space on AirBnB for travelers. Having a roommate is the more passive of the two, as being an Airbnb host will require more work in the form of turning over the room between stays. This is a super painless way to earn $500 to $1,000 a month without much effort – you may even be able to cover your mortgage payment with this extra income!
The second big takeaway for me, was to pick a niche you know, you find interesting AND where there is demand for your product – ie willingness to buy/pay.  A lot of people only remember the first part of this 2-part formula, and end up creating a blog on knitwear for kittens.  But it’s the overlap of passion and profit that Ferriss stressed so much.