You need to want to change who you are to actually do something about it. My brother still has a drinking problem and I'm a former addict. My turning point was developing schizoaffective disorder. If my medication didn't negate the high of cocaine and other uppers, I would still be (ab)using them. If I didn't think my family was plotting to have me executed by the syndicate everytime I smoked some weed, I'd still be smoking it.

Usually it takes something serious for any addict to want to quit on their own. The most prevalent being a health scare, or health concerns. If I didn't gag everytime I smoked a cigarette, I wouldn't have even thought about quitting.

Sometimes people can recognize the warning signs and they will turn their life around. If you can be persistent when voicing your concerns, (if he shares health issues with you) then maybe you can drill the thought into his head that things can't continue this way.

My brother told my dad about some health problems he'd been having due to his alcoholism, but even my dad, a former alcoholic, knew that ultimately its up to him to change, so he didn't say anything about it. and if he's going to change, its up to him to get his **** together.