Change up from the habits you associate with smoking. And it's not easy because it takes a long time to become comfortable with your new routines (six weeks ish).
Your brain is hardwired to expect a nicotine and Dopamine fix (when you reward your brain, you get a dopamine hit to say thank you). So you need to get rid of te dependence on nicotine and also reward your brain differently. Have a cookie, cup of tea, go for a walk/run, etc.. Your brain will eventually dose out the dopamine for the new habit instead.
Quitting cigarettes is a very rewarding and difficult thing to manage effectively. The first 3 weeks are the hardest but the difficulty Then, (once physical dependence is overcome) becomes a more subtle beast to manage. The key, for me anyway, is to avoid the circumstances that make you want to smoke again.
But it is worth it and I am glad did it.