I know (not well anymore) someone who owned a business (multiple I think) who's said that same saying and I'm sure I've read it somewhere else. I always assumed it meant: when you have a business treat yourself as an employee and pay yourself so that you don't use all the money (on business needs is all I can think of: staplers, paper, etc) and can pay your bills.

I might have misunderstood it or whatever but I always thought it made a bit of sense since you need to take some money home at the end of the day.