The trick is knowing whether or not you're financially disciplined. And usually one finds out the hard way. It often involves a credit card or credit facility of some nature.
My wife for example does not have this ability, however I can manage it by basically controlling the amounts we have and putting restrictions on how money is spent that teach the lessons of saving that her parents for some unknown reason skipped teaching her. Lessons like 'you have X amount of cash lets save up for that thing you want' 'lets review our purchases and see if they make sense on the amount of income we have' 'yes, your friend has a need of 100 bucks and we can cover it but will giving them 100 just make them ask next time for 1000 and will it actually fix their problem or delay it?'
My wife is 99th percentile for trait conscientiousness and I'm 1st percentile. I'm amazed at the amount of money she's able to save and her level of discipline and she's generally gobsmacked at the amount of money I waste and the random shit I buy.
Having the information about what one should or shouldn't do is only part of the equation. 8t also needs to be something you can apply, and sadly some of us just can't.