I tell every veteran (or family member of a veteran), or people still in service or people with a family member still in service, I encounter "Thank you for serving". Most react with surprise, then say "thank you". No, I say, don't thank me, YOU served (are serving, or the family also serves).
This often happens at work and the other day N heard me say it to a customer, and said "oh that's so nice of you". I said I don't say it to be "nice". I say it because I mean it. I tell our PD and FD guys thank you, too. Again, I mean it. I am grateful for all these people who do something I would not be able to do. They work to protect everyone. It's huge.