I am not referring to smoking cessation. I don't have any experience with that myself but I understand it is very difficult and usually takes many attempts to be successful. The question is whether it is easier or at least more advantageous to wake up one morning and never smoke another cigarette or to try to gradually wean yourself off the habit by smoking one less a day or using some kind of filtration system that gradually reduces the amount of nicotine. You can wear a nicotine patch or chew special gum to try to assist your self. But as Yoda said, "Do or do not; there is no try."
What about if you want to make a serious change to your relationship with money. Spending Fasts are a version of cold turkey. You commit to only paying for essentials and define bills very strictly. Maybe you only eat what is in your freezer or on your pantry shelves. You pay your rent or mortgage and utilities. It would be expecting too much for you to sit in the cold and dark or huddling around a solitary candle. It doesn't help you to damage to credit rating by not meeting financial commitments you made, even if done rashly. For some/many people omitting shopping, paid entertainment and socializing is difficult. But lots of people have declared their intention to the world and left blog posts online for you to peruse at your leisure. Presumably only the successful ones wrote a post about it the others cowered in shame and hoped no one noticed.
But realistically, making serious changes to your spending habits as well as your approach to your finances can be done gradually, in stages, and there is an argument to be made that it will work better in the long run if done that way. Unless you are facing bankruptcy, you can be a little gentle with yourself. But only a little!
It is best if you have a goal to focus on when the going gets tough. You want to live longer, be healthier, set a good role model for your children. This applies to both the cigarettes and your finances.