I was a pretty average (by Danish standards) consumer of alcohol (for my age) from ages 14 to 31. I'm 36 now, so I've not consumed any alcoholic beverage at all for 5 years.
Danish drinking culture is a bit on the heavy side, and I enjoyed getting absolutely shitfaced, I generally didn't have blackouts or do anything too silly, but the hangovers started getting really serious.
One day, with "yet again" the worst hangover in my life, I decided the hangovers were not worth it, and that whatever magic I felt in the drunkenness, was ephemeral, it'd never lead me anywhere, it'd never become real, it'd never truly make me feel good.
I stopped drinking the same way I stopped smoking after a 20 pack a day for 8 years. Simply didn't do it again. I didn't throw out all the alcohol in the house, just like I didn't throw out my half-finished pack of cigarettes..
Eventually, visitors drank the rest of my whiskey and beer, and eventually the cigarettes were thrown away eventually, but they were deliberately kept around for a long while first.
I kept them around due to an insight I had from a previously failed _attempt_ at quitting smoking, which was that.. If I had no cigs, my brain would constantly be looking to ways to get me into novel situations where I might act on impulse.. Like, "oh, maybe you should go get your car washed, then you can also refuel" -> "me goes filling up car, goes into store to pay for gas.. bot-mode kicks in and I impulsively buy a pack of cigs..".
I figured that, if my temptations are out of reach, I will accumulate activation energy to obtain said temptation, and when that energy is discharged, and temptation acquired, there's too much momentum to stop mid-way, and I will indulge.
If the temptation is constantly around, no energy is built up, so no momentum, and it makes it very easy to simply look at the can of beer, or half-smoked pack of cigs, and go "yeah, I could reach over and do that, and I'm not going to", constant presence, constant control..
I hate to use the term, but maybe it's a form of mindfullness, being absolutely constantly aware of this thing so you never build up any kind of mental momentum towards it.
It's been so long, and I no longer have any desire for alcohol or tobacco, I enjoy the taste of beer, and I often drink non-alcoholic ones, many of which are great, and perfectly acceptable in social settings as well.
I don't have any trouble saying I don't drink, if pressed on the subject, I explain it as it is, that I've been as drunk as I've ever needed to and that the experience has nothing more to offer me, and that I will guarantee that I can be just as (insert politically correct word of the day) without the assistance of alcohol.
Sometimes people then mention taste rather than intoxication as an argument and I explain that while I really enjoy the taste of red-wine, I also think cola goes well with just about anything.