Don’t ever say “Quitting smoking is hard!” If you are saying that, you are practicing self-hypnosis.
Instead say, “It is possible to quit smoking,” or, “I am going to be a Smo-no-ker!”
Just be convinced that, one day, you will be a Smo-no-ker. Then, you are allowed to look back and say, “Quitting smoking was hard!” as a way of reminding yourself you can do hard things. And, once you know that, you will be able to tackle many other “hard” things in life that you had been putting off because they were “hard.”