Honest, lasting personal finance improvement takes time and requires many actions. However, in my book, there is still only one must do action to improve your financial situation. Even if you do all the other “responsible actions” with your finances, without this one action your finances will never be as awesome (or satisfying) as they could be.
No, I’m not talking about budgets.
Improving your credit score.
Automating savings.
Or paying off your credit card debt.