The craziest part of this was I’d wake up in the morning and there would be more money in my bank account, from people who had bought my book overnight. When you think about it, an online store that sells something that’s digital is something that’s open 24 hours a day, 7 days a week, 365 days a year. Using tools, software and systems, you can automate the delivery process so you literally don’t have to do anything to serve that audience. That’s super powerful.

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.