Today is the start of the Christian season of Lent, the forty day countdown to Easter during which many prepare by trying to give something up. I guess that, for them, LENT must mean Long Endurance No Treats? Whatever, we all have bad habits we'd like to give up, whatever the season. And we all know how devilishly difficult it can be.
As an example, let's take cutting back on heavy coffee drinking. The trick is not to think you cannot or must not have that next coffee. That only gets you thinking about coffee, which dooms you to cave in to your craving.
A more effective way is to simply make a deal with yourself, in which having a coffee always loses out to an alternative choice. For example, choose someone you love dearly. The deal is that before you have a coffee, you first spend a few moments thinking loving thoughts about that person. You then give yourself a choice. Do you want to continue thinking blissfully about your loved one? Or would you prefer to go for a coffee?
Not only does drinking coffee (or whatever it is) soon become a thing of the past, you are also creating a good habit in place of the old one.
Perhaps you could buy some flowers for your loved one, with the money you save on coffee. They will enjoy your flowers, you will enjoy better health (both from drinking less coffee and from thinking loving thoughts throughout your day).
And when they ask you why you have given up coffee, you can answer truthfully, "I did it for you!"