This is a question posed in Robert Kiyosaki’s famous book Rich Dad, Poor Dad and refers to financial independence. In other words, have you accumulated sufficient income producing assets that would give you the freedom to stop working for ever?
The emphasis is on income producing assets because non incoming producing assets are illiquid and therefore would need to be sold to release capital. The obvious example being your home; you could downsize to release equity but it may be at a time when you are not emotionally ready to or when the market is falling.
Your business could be viewed as an income producing asset but as I have mentioned in a previous post relying on your business for financial independence is a risky game; your future is reliant upon factors outside of your control: competitive forces, the quality of the management team, economic conditions and legislative changes for example.
A more secure strategy is to accumulate income producing assets that are diversified. The typical ones being buy to let properties (I covered the downsides of this investment that people are usually blind to in another post), pension funds, ISAs, savings and unit trusts.
As you build up wealth the more you keep away from the tax man (legitmately of course!) the greater your wealth will be and the sooner you can stop working.
This is not something to put off to another day. The sooner you start building up wealth that is independent of your business the sooner two powerful forces will start working for you: the power of compound interest and the re-investment of income. £10,000 invested today and receiving 5% pa growth would be worth £15,510 in ten years time and £25,270 in twenty years.
I covered the power of re-investing dividends in this post but as a quick example: if you invested £10,000 in the FTSE All Share between 1994 and 2014 (a period including two large stock market crashes) the value would have increased to nearly £23,000 if you spent the dividends as they were received or, nearly £45,000 with dividends re-invested. You would have had the benefit of the dividend income in the first scenario but the total return would not nearly be as close.
There is another way to look at the title question: how long would you survive mentally and emotionally but that is for another time.