Here is an idea how to change the influence of narcotics on a person if the humanity still can't overcome drug addiction. We have to change "grass" genetically.
A person addicted to drugs i.e. mostly pot would still take a dope and be in an almost permanent state of high but the "grass" would start to "work" and influence his brain only under condition of working load of the organism i.e. this person should be engaged in sport or some manual labor by the time of "taking a dose".

If it's impossible to give up, it is necessary to change the influence on the human's organism. Further, drug addiction should be worked out in regard of physical load on the organism, and step by step drug addiction should be substituted by, say, Internet addiction or sport addiction and so on.

Hope for the reasonable comments.

As for me: I had a drug problem in my childhood:
I was drug to church on Sunday mornings.:D