(1) First you're forced into quitting because your sources dried up, your dealer dropped off the face of the earth, yo moved to a new town where you don't know anyone, etc.
(2) Once you get over the initial annoyance of not having access to marijuana, you adjust to life as a nonsmoker and realize there is nothing catastrophic about it.
(3) You start thinking about all these negative associations with the weed and start attributing past blunders and failures to marijuana use (whereas it was probably alcohol that was the cause, which you've begun to drink more of because you no longer have any weed to smoke).
(4) After a few weeks of not smoking, you start thinking, "Wow, it's been a few weeks and I feel fine. Maybe I'll just never smoke again. After all, it was a pretty expensive habit."
(5) Now, you've become a voluntary non-smoker. Your local contact might be back up and running, but you're keeping away from that stuff now. People in this stage often hold deceitful notions like, "Now I have my life back," and, "My friend X still smokes -- man I remember what it was like back when I used to make poor decisions like that."
(6) You might even start persuading your friend X to join you in the world of the living.
(7) But hopefully your friend X has his brain, dick, and heart all in the right places--i.e., now it is up to X to (a) ignore your efforts of persuasion and (b) counterpersuade you to come back to the Dark Side.
(8) If X is persistent enough, then sometime when your defenses are lowered (e.g., at a party), X will persuade you to take a puff, and you will give in.
(9) Welcome back to the Dark Side! You know where you are? You're in the jungle, baby!
(10) Since you only smoked during a party or something, you may not yet have had a really convincing high to bring you back into the fold; it might have been shortly before passing you, you might have been drunk, etc. But you're now a little more amenable to smoking during the day and experiencing a classic daytime high. And once that happens, and you find yourself simultaneously composing music, checking off all your neglected to-do's, exercising, stretching, preparing bolder and more complex dishes than anytime during your stint as a nonsmoker, etc., then you realize the web of lies in which you'd been increasingly ensnarled. You're stunned by how amazing a marijuana high is, and you regret having gone so long without that experience.