Even a success rate of 50% would be startling. I don't believe it.
Which is ironic, because the Wikipedia page you just linked to says that "95% of former smokers who had been abstinent for 1–10 years had made an unassisted last quit attempt", with the most frequent method of unassisted quitting being "cold turkey", about which it was said that:
53% of the ex-smokers said that it was "not at all difficult" to stop
Of course, the page also says that lots of people don't successfully quit, which isn't incompatible with what thomblake says. Among people who are able to congruently decide to become non-smokers, it's apparently one of the easiest and most successful ways to do it.
It's just that not everybody can decide to be a non-smoker, or that it occurs to them to do so.
Anecdotally, my wife said that she'd "quit smoking" several times prior, each time for extrinsic reasons (e.g. dating a guy who didn't smoke, etc.). When she "became a non-smoker" instead (as she calls it), she did it for her own reasons. She says that as soon as she came to the conclusion that she needed to stop for good, she decided that "quitting smoking" wasn't good enough to do the job, and that she would have to become a non-smoker instead. (That was over 20 years ago, fwiw.)
I'm not sure how you'd go about prescribing that people do this: either they have an intrinsic desire to do it or not. You can certainly encourage and assist, but intrinsic motivation is, well, intrinsic. It's rather difficult to decide on purpose to do something of your own free will, if you're really trying to do it because of some extrinsic reason. ;-)
Which is ironic, because the Wikipedia page you just linked to says that "95% of former smokers who had been abstinent for 1–10 years had made an unassisted last quit attempt", with the most frequent method of unassisted quitting being "cold turkey", about which it was said that:
wedrifid is asking for P(success|attempt), not P(attempt|success), and so a high P(attempt|success) isn't ironic.
Change blindness is the phenomenon whereby people fail to notice changes in scenery and whatnot if they're not directed to pay attention to it. There are countless videos online demonstrating this effect (one of my favorites here, by Richard Wiseman).
One of the most audacious and famous experiments is known informally as "the door study": an experimenter asks a passerby for directions, but is interrupted by a pair of construction workers carrying an unhinged door, concealing another person whom replaces the experimenter as the door passes. Incredibly, the person giving directions rarely notices they are now talking to a completely different person. This effect was reproduced by Derren Brown on British TV (here's an amateur re-enactment).
Subsequently a pair of Swedish researchers familiar with some sleight-of-hand magic conceived a new twist on this line of research, arguably even more audacious: have participants make a choice and quietly swap that choice with something else. People not only fail to notice the change, but confabulate reasons why they had preferred the counterfeit choice (video here). They called their new paradigm "Choice Blindness".
Just recently the same Swedish researchers published a new study that is even more shocking. Rather than demonstrating choice blindness by having participants choose between two photographs, they demonstrated the same effect with moral propositions. Participants completed a survey asking them to agree or disagree with statements such as "large scale governmental surveillance of e-mail and Internet traffic ought to be forbidden as a means to combat international crime and terrorism". When they reviewed their copy of the survey their responses had been covertly changed, but 69% failed to notice at least one of two changes, and when asked to explain their answers 53% argued in favor of what they falsely believed was their original choice, when they had previously indicated the opposite moral position (study here, video here).