I don't think it's possible not to affect others. The smoke
affect others to various extent no matter how careful you are to
avoid smoking near them.
And also affecting yourself also not so responsible la... ur body
is given by your parents, dont destroy it and die a terrible death.
You know.. suicide also have bad karma. Doesn't mean if I don't
affect others I won't have bad karma. And anyway if you die you
will affect your family also.. so... think deeper.
Also.. Buddhists believe in rebirth, and our habits deep latent in
our consciousness will be brought forward to future lifetimes. So
not only will you shorten your current life you might shorten your
future lifetimes (by smoking again) It is better to clear whatever
habits we have in this lifetime.
But that's still not the crux of the matter. Smoking involves deep
craving, and in Buddhism, craving is dukkha. This form of
addiction, craving, is what Buddhists want to get rid off through
practise. So even if you smoke now... eventually you will have to
learn to let go of such addictions, and in fact, all addictions.
There are some teachers who are highly enlightened.. highly
realised and haven't really stopped smoking, but eventually one has
to learn to let go of them, because it's really a fetter. So in
terms of stages of enlightenment, the Arhat path (stream enterer,
once returner, non-returner, arhat), by the time one reaches the
'Once-returner' (still a bit left) or 'Non-returner' stage he would
have cleared all sensual cravings. That is even before one reaches
the stage of Arhat. That is... one experiences the highest bliss of
Nirvana at all times and has no fetters remaining. Also as we
said.. as Buddha said.. buddhism can be summarise as, "do good,
avoid evil, purify the mind". Purify the mind is the most important
part, we must cleanse it, eliminate until nothingness, not a single
bit of defilements, habitual energy, ignorance is left.