I never discussed it with anyone while I was working toward FI (except certain members of my family). If a co-worker poked fun at the fact that I ordered water at a restaurant, I'd just say "why pay $2 for tea/coke, when water is just as good, and free?"
I retired at age 43. But after a few years of RE, I was slowly dragged back into the work force on my own terms (primarily working from home, no more than 40 hours per week, no BS meetings, not being forced to wear a tie, and avoiding a few other chicken squat "rules"). At that point, it was kinda hard to hide it. Now, I just tell folks that my wife and I are frugal, that we are FI (I never tell them that we are multimillionaires, though). You'd be amazed at how many people are not scornful, but rather ask for advice.
So I guess I'm far more open about my "secret life" here than in real life :) It's kind of weird that a lot of us find it better to "keep in the closet" about being FI.
And yeah, I still order water at restaurants...