A financial hack to spend less money, for say a week is for you to withdraw the amount of money you have to use that week and then avoid making any payment through your banking digital applications. There is a psychology behind this and why I think so is because if you withdraw cash that you need for the week and then have it at hand, you will not want to see that stack of cash go down very quickly so you will be cautious with transactions you make, but when making transfers using your mobile bank application, since you do not see a physical value of what you are spending, you can send out a huge amount of money and if feels like nothing because you did not see a physical representation. The ease of transferring money has made keeping money more difficult in bank applications, and also financial discipline harder to practice for some.
Have you observed this?
The world has passed this stage, if you are at least an adult with basic responsibilities this won't work because you will probably be spending more than you think.
I say this because the world is very digital right now, there are places you go and they tell you that they don't accept cash or you might be in a situation where you are far away from and the only solution is sending money digitally now you out yourself through the stress of looking for how to do that and this problem can come anytime of the day.
The best solution is not holding cash because aside the points I mentioned cash can easily get stolen or misplaced, you can have a designated account like for emergency fund, monthly or weekly expenditures and one for saving(although saving in fiat is not wise better to invest in assets)