Being a non-drinker is no hassle whatsoever, at least until around lunchtime, when everyone begins asking what's wrong.
At breakfast-time, no-one will bother you. You are not expected to pour gin on your conflakes and no-one will mind if you refuse to put a dab of Stella Artois in your coffee.
Abstaining from alcohol would not be a problem for teetotallers, if only they didn't have to answer constant questions from people.
"Why don't you drink?""
"Did you ever drink?"
"Can I buy you just one drink?"
"Do you ever have fun?"
"What do you do to unwind?"
The notion that I need a particular type of liquid to unwind is an unusual concept. For a non-drinker, relaxation can be achieved through numerous other means. For example, one of my favourite ways to unwind is simply to sit down. This is achievable regardless of what I drink. In fact, I can continually stand up and sit down throughout the day and will face very little impairment as the evening progresses (unless I come across some unexpected tiredness).
The hardest experience for any non-drinker is going for a meal. The sitting down and eating of the meal is simple enough, but dealing with the judgemental looks from the people you're with consumes a lot of energy.
"Are you sure that coke is really all you want?"
"Is that really just water?"
"Can I buy you one drink, just one?"
After dessert, everybody at the table will order a tea or coffee. This is the one time when everyone is okay with you having a non-alcoholic beverage. You may even hear a bona-fide alcoholic say "I really need a coffee."
After these hot beverages are consumed, everyone apart from you will return to alcohol. If you attempt to order another coffee, people will look at you funny and demand you lighten up.
For me, I've never understood why it's a big deal. Some people don't like the crusts on sandwiches, some people refuse to try sushi and yes, some people don't drink. I never feel the need to ask, "why DO you drink?" - so you needn't ask why I don't. I just don't.