What’s the point of asking for opinions if this is what you think of opinions different than yours.

Can you disprove all mediums? What if someone has an experience with them that they can’t explain but felt powerful and they made a personal choice to believe that they did talk to a dead relative.

it is not irrational, to observe (or experience) something and not being able to explain it.

I agree, and that’s where I would stop, I can’t explain it, I don’t know what this is.

I think in general it matters what we believe to be true or not, you might think that in a certain situation believing a false thing can result the same (or better) way than not believing but beliefs are not restricted to certain situations and will inform our decisions elsewhere, maybe with more dire consequences. A quick example would be mediums who pray and scam grieving people out of time and money.

Isn’t it irrational to believe in things that cannot be proven or disproven?

Cold turkey is what works for most people but if you tried it and failed many times don’t be afraid to use nicotine replacement in some form, medication ( I used Champix and I’ve quit successfully 3 years ago) or even therapy. You’ll find online a lot of people who say that you only need willpower which is true if you have it but just depressing if you don’t making your situation after numerous quit attempts worse and worse.

There are plenty of websites with concrete plans and tips on how to do it, all of them with good advice but you have find out what works for you and what doesn’t. There are also some apps that can help you track your quit process, the health benefits of quitting and reward you.

Since you told nothing about your previous attempts if you had any or how long youve been smoking and why you want to quit I can only give some general advice:

Every day you don’t smoke is a win. You need to find out why smoking hurts you, why stopping smoking would help you. Choose a plan, stuck to it and if you fail learn from it.