Or... In my case it has been...
Have "just one" down the pub, and enjoy it, and have no further cravings...
The following week...
Have "just one" (after all it worked last time)... and maybe another one... and have no further cravings...
A few days later having a bad day at work... 'Borrow' a smoke of a work mate... It's fine... You aren't addicted anymore... Smoke it... and have no further cravings...
It's the weekend again... So you borrowed about 3 or 4 tonight... no big deal... no cravings
Damn those Monday morning blues... buy a pack on the way to work, and smoke "just one"... still not got a craving... pretty sure anyway...
Monday night, you had a crappy day at work... Well... You've got a pack now... may as well have another one... or two...
Tuesday morning after getting to work... ya know... I've got that packet of smokes... May as well have one...
A few hours later... another one wouldn't hurt...
etc...
And within a blink of the eye you're on a pack a day again. This is the slippery smoke.
I've said it before and made myself very unpopular, you can have "just one" with no particular repercussions if you have the will not to have another one, however, it is VERY easy to have another one... and another one... and it's those ones that will get you hooked again.