The hardest part of telling people you have stopped drinking is not the telling. It is the having to do it more times than you expected, with different people asking for different versions of the same conversation.
There are roughly four kinds of person who will ask. They want different things. Knowing which one you are talking to lets you give them what they need without giving more than that.
The curious neutral
This person has noticed you are not drinking and is asking out of genuine curiosity, not concern. They want a short, light answer. They are not asking for the long version.
What to say: "I'm not drinking right now." Optional follow-up if they keep going: "I just feel better without it."
What not to say: anything that turns the moment into a Big Conversation. The curious neutral is making conversation, not interviewing you.
This is most of the people who will ask. Give them the short answer, change the subject, move on.
The fellow traveler
This person is asking because they have thought about cutting back themselves. They are interested in your experience because it is information for their own decision-making.
What to say: a slightly longer version. Something concrete about what changed for you. Sleep, money, mood, time, social patterns. The thing that actually moved.
What not to say: anything evangelical. This person is taking notes, not asking for advice. Let them lead the follow-up questions. Do not advocate for them to quit. Just describe what your experience has been.
The defensive
This person is asking because your not-drinking has highlighted their own drinking in a way that is uncomfortable for them. They may be challenging, dismissive, or making jokes that are slightly too sharp.
What to say: the shortest, calmest version. "I just feel better without it. It's working for me." Repeat as needed without elaboration.
What not to say: anything that engages the implicit challenge. They are not actually asking why you stopped. They are looking for a way to feel okay about not having stopped themselves. Engaging the challenge does not change their mind and does damage the relationship.
The defensive person is the one most likely to require a "no, I really am not having one" repeated three times. Do not soften it. Do not over-explain. Do not get defensive in return. Hold the line calmly. The conversation ends faster that way.
The worried
This person, usually a parent, partner, or close friend, is asking because they care and they are trying to understand whether something is wrong.
What to say: the most thorough version, but only of the relevant parts. They want to know that you are okay. They want to know whether to be concerned. They want to know whether this is permanent.
What not to say: anything that minimizes their concern. They are not being intrusive; they are paying attention. Acknowledge their care, answer the actual question they are asking, and let them know what kind of support you do or do not want.
For partners specifically: this conversation should happen explicitly and not be assumed. Partners adjust to a partner's new posture better when they are included in the decision-making rather than informed of it. Even if the decision itself is not theirs to make.
What about family events
The family-event version of this conversation is its own subgenre. Aunts and uncles and grandparents whose model of social drinking is fifty years old and not particularly current. They will offer wine. They will be confused when you decline. They will try again later.
The strategy is simple repetition and grace. "I'm not drinking right now, but I'd love a club soda." If they keep offering: "Really, I'm good, thank you." Do not explain. They are not asking for explanation; they are asking for a familiar social script, and the simplest version of the script is the one where you just keep declining politely without justification.
Most of them adjust within two events. A few never adjust. You do not need them to adjust. You need them to stop offering, which they will eventually do.
The question they are actually asking
In most cases, the question "why aren't you drinking" is actually "are you still you." People are checking whether your stopping changes how you are with them. They want to know whether the friendship is still the friendship, whether the dinner is still the dinner, whether you are still the person they have known.
The most useful thing you can do is keep being you. Show up to the things you would have shown up to. Be present in the same way you were. Order the club soda confidently. Make the same jokes. Have the same conversations.
The not-drinking is much less interesting to other people than you think it is. The version of you they care about is still here. The drink in your hand was never the thing.