Its always hard for me to avoid unnecessary expences, I like to enjoy every day of my life and dont care much about my future.
I use to hide my funds to dont let my eyes notice it, to make my braint forget about it. I may give some of my funds to my relatives because I beleive they are able to keep it better. Cold bitcoin storage is also good solution for it
I really do not see anything hard here as all it takes is just discipline and knowing how to control the way you spend and with that being said, controlling your spending is not something that can just be done with your mind, brain or hands, you need to always learn how to make a list and write what you really need, what you want, which the latter are mostly things that are not really necessary. As long as you can do this and stick with it, with some level of discipline, you will see yourself spending more responsibly and notice that you have been extremely wasteful most of the time on things that are really not that important.