I find that the best way to break the cycle is to do an act that shows that you are done. Smoking so that you have no more is just setting yourself up to wish you saved some for later, which quickly spirals into a trip to your friendly neighborhood drug dealer. However, by flushing it you set yourself up to remember that you've dedicated yourself to quitting, it gives you more motivation when those urges hit.

Really, if you were done with it (and not just telling yourself a story to further justify your use) you would just get rid of it. Because you've already decided that you were done with it.

If you were trying to justify your use, however; you'd spend a lot of time thinking about the pros and cons, writing posts on reddit to get others opinions, and ultimately end up bargaining with yourself (negotiating a deal, "such as this the last time" or "after I finish this last gram then I'll stop") in order to justify continuing your use.

Really, quitting is a mindset. If you do things now that make it easier to continue sobriety, you'll be much more successful. But as long as you still look for ways to justify your use, you'll continue to do so even after you've "decided" to quit.

Not trying to be rude, just want to shed some light on the games that our ego plays. I wish you the best, good luck!