I definitely agree that finding friends who drink less can be very helpful. But I do want to chime in that not everyone finds that their friendships are built on alcohol. So it's not necessarily true that you need to completely drop your friends.
Each situation is different. But in my case, I didn't lose any friends over my change in drinking status. I have some friends who like to party, but that's not the only thing they do, so I just spend more time with them when they're doing other things and less when it's a party. But even at the parties, because these are people I genuinely enjoy being around and who are interesting to talk to, I tend to enjoy myself even when there's drinking.
YMMV. Just wanted to point out that there are different situations possible!