Many addictions are thoroughly enjoyable but ultimately harmful. Smoking
is one such addiction. Some people shy away from the term "addiction"
due to all of the horrible connotations, but absolutely everyone is
"addicted" to multiple things. The addiction might be a substance like
nicotine, or the addiction might be a mannerism, or the addiction might
be over-eating, or the addiction might even be a way of thinking, but
none the less, human beings are always creatures of habit.

There's an old and jaded phrase, "You're unique, just like everyone
else." The same can be said about addiction, "You're addicted, just like
everyone else." When put in such simple and straightforward terms, the
commonality of harmful addictions like smoking shines through. You're
not the first person or the only person with a harmful habit. The good
news is that we can change our habits. The bad news is that changing a
habit takes effort.

The problem is not smoking itself since if only done on rare occasions
it can be exceedingly pleasurable, instead, the real problem is the
habit of smoking. It's the _repeated_ and _extensive_ exposure to smoke
entering your system that eventually kills you. The rates of emphysema
and cancer (lung, mouth, throat, stomach, colorectal, ...) due to smoke
exposure are extremely high in poor places where people cook their food
over open flames or burn wood for heat without adequate ventilation. If
you are a habitual tobacco smoker, then you're certainly not the only
one killing yourself with smoke, and unlike you, many must endure the
smoke to get the food and heat they need to just survive. You have it
easy. You have a choice.

The harmful habits are reinforced by the positive feedback of pleasure.
Another old and jaded phrase, "Too much of a good thing," comes to mind,
but the misguided phrase, "All things in moderation," is dangerous. The
trouble with the idea of all things in moderation is some things are
simply too addictive to even try, so they pose an irrational risk of
addiction. Nicotine is _immensely_ addictive on a chemical basis. In
fact, the neurotransmitter receptor often used to measure the addictive
qualities of substances is actually named after nicotine:

https://en.wikipedia.org/wiki/Nicotinic_acetylcholine_recept...

You may, or may not, understand all the biochemistry involved, but most
people can understand the logic of how a simple chemical compound like
nicotine can cause a pleasurable response, and the pleasure can lead to
a habitual addiction.

If you are already addicted to a pleasurable but harmful habit, a mental
trick to solve the problem is to decide to never quit, but also decide
to break the _habit_ of pursuing your addiction regularly. You can
harness your inner procrastinator to your advantage by simply saying,
"Maybe I'll have a smoke later," when the urge hits you. Over time, the
beneficial procrastination gets easier and easier. The common "Smoking
Cessation" products, both prescribed and over-the-counter, like nicotine
patches, gum, and mints may be helpful in your procrastination efforts,
but be wary of the all too common problem of replacing one addiction
with another.

Some have claimed that "electronic cigarettes" (e-cigs, vaporizers,
vape) are useful for smoking cessation, but I have not personally seen
any peer reviewed research results to support such claims. Similar to
the proven "Smoking Cessation" products (patch, gum, mints), the e-cigs
can provide nicotine in a form other than smoke, but since the nicotine
itself is addictive, you still have the same substantial risk of merely
replacing one addiction with another. The common claims nicotine infused
e-cigs being harmless are pure bullshit -- There is a reason why all the
major tobacco companies now have their own brands of e-cigs; they want
you to become addicted.

https://www.ncbi.nlm.nih.gov/pubmed/26270431

http://www.ccjm.org/cgi/doi/10.3949/ccjm.82a.14054

>ABSTRACT

>Electronic cigarettes (e-cigarettes)—devices that generate a nicotine
vapor that can be inhaled by the user in a fashion that mimics the
experience of smoking—are increasing in popularity, and many people
seem to view them as reasonable alternatives to nicotine replacement
therapy to help them refrain from smoking. Physicians should not
encourage such a view. E-cigarettes are unregulated nicotine delivery
systems that have never been subjected to any kind of testing of safety
or of efficacy as nicotine replacement therapy. Moreover, for young
people who have never smoked, these devices could potentially serve as
a gateway drug.

The claims of nicotine itself being harmless are also bullshit.

Nicotine itself causes cancer (i.e. it's carcinogenic). You don't need
to be a genius or even particularly adept in chemistry to realize how
nicotine is carcinogenic due to how it reacts in the body. Without being
too fancy or confusing, when Nicotine loses its methyl group, it becomes
Nornicotine which when exposed to mild acids (syliva, digestive tract,
lungs, or even acids in blood) becomes Nitronornicotine (NNN) which
_IS_ classified by the International Agency for Research on Cancer
(IARC) as a Group 1 Carcinogen.

Smokers die of colorectal cancer, but it's not due to being assholes,
instead, it's due to simple chemistry that everyone can understand.

https://en.wikipedia.org/wiki/Nicotine#Carcinogen

https://en.wikipedia.org/wiki/Methyl_group

https://en.wikipedia.org/wiki/Nornicotine

https://en.wikipedia.org/wiki/N-Nitrosonornicotine

https://en.wikipedia.org/wiki/Group_1_carcinogen

Yes, wikipedia disagrees with me about nicotine being a carcinogen, but
wikipedia is dangerously wrong. The above linked pubmed paper is a good
place to start reading (references) about the role nicotine plays in
carcinogenesis, but there is a lot more research out there if you dig.
The tobacco (and e-cig) industry is continuously doing everything it can
to prevent nicotine from being properly classified as a carcinogen by
the International Agency for Research on Cancer (IARC). The editing wars
on the wikipedia nicotine page between the tobacco industry and health
(research) professionals are staggering and notorious. You do not need
to be a conspiracy theory kook to see all the blatant corruption and
manipulation at work under the guise of fake "neutrality" on wikipedia.

Additionally, since nicotine is an effective appetite suppressant, you
can expect to be hungry. Unless you can avoid replacing the satiation
pleasure of smoking with satiation pleasure of eating, you will gain
weight, possibly a lot of weight. In this overly image conscious world,
the very idea of possibly getting fat(er) can be reprehensible enough
for some to chose smoking over weight gain -- This is a false dichotomy.
Using a fallacy of false choice to justify a continuation of a harmful
habit is simply irrational. Human biology has evolved to both crave
salts, fats, proteins, and sugars for survival, so the risk of replacing
a harmful smoking habit with a harmful eating habit is very significant.
Once you learn to harness your inner procrastinator to defer smoking
(indefinitely), you may need to also harness it to eat less by deferring
eating until later. Also, when you do mistakenly gorge yourself on food,
you'll notice something extremely odd, namely, you're still hungry, so
you'll eventually learn how eating fails to actually solve the (new)
problem of a perceived hunger sensation/craving. Small snacks of low fat
cottage cheese (or tofu) and fruit may help, and some healthy salt cured
foods like olives and pickles may also help. The goal is to have a small
amount of reasonably healthy food that checks off all the required boxes
(salts, fats, proteins, and sugars).

Your friend may be (rightfully) skeptical, but one of the know ways to
stop smoking is refusing to quit, and surprisingly, the procrastination
method works well for breaking or changing all sorts of harmful habits.
I wish your friend the best of luck.