I used to drink a ridiculous amount. I lived in central London and could walk home from pretty well everywhere I socialised - sometimes it would talk a few hours but I enjoyed walking so no prob.
I stopped first when I realised I was deeply unhappy in my job, was very ill, and took the opportunity to become self-employed, with a consequent loss of disposable income. So no more boozing.
That lasted about 5 years, and then I got married. DH as more of a drinker so I joined in. Not for very long though, I became pg and it was the easiest thing to just stop drinking again (I was quite thankful for the excuse, it turned out!).
I've never really got back into it. DH being a musician meant that he was out a great many evenings which left me at home with the baby. I'd never been a lone drinker, had only really done it socially anyway so was not tempted to drink when alone at home with dd.
I do drink occasionally. I became ill again (ms, had massive attack) and have never fully recovered. This means that evening socialising is rare as I'm too tired. We don't often socialise at home, but when we do I'll have a glass of wine. I'm not really interested in having more than that as it just sends me to sleep.
So I've gone from being able to drink huge men under the table to not being able to hold even one drink well! I don't get hangovers though 