Very often people conduct their business poorly. They spend their profit before the year is out. In the case that you are employed you should still treat your work as a business (if you want money that is). You should be able to show profit at the end of the year and ideally you should keep that money and not spend it unless it is returning with more profit. E.g. you should invest it in the bank.
Profit is the one thing that at the end of the year you can say I put in all those hours and I have this to show and for that reason it is important to take care of it.