I’m for most part really sincere when I smile, but sometimes I force myself to do it in certain situations, because I dislike showing what goes on in my life, be it very good or less than desired, let me explain.
In a time of social media where everyone tries really hard to show they are living a full happy life, I hide myself behind a smile so I don’t need to share any of my life, and I go to great lengths to keep anyone I don’t trust away from my daily life.

Having 3 kids, a loving wife, some good friends and a lot of hobbies fills all my time from first light until dawn, but I always try to hide the fact I’m tired or even burned out.

At work people expect me to do my job the best I can. I’m paid to deliver a service with sympathy and professionalism even if sometimes I do feel like a road wreck.
I’m fortunate enough to work with really nice people and my current client is probably one of the best I worked for. At work I often have a sincere smile and visitors do notice if I’m not in a good mood.

Outside work I smile from time to time, a polite but sometimes tired smile, I don’t have a hard life but I do have a lot of things going on at all times.
I’m now a very accessible person, mostly because of my work but I wasn’t always like that, I do have a “darker” side, my wife knows it well, I judge people really fast because of my work, this means I can in a few days understand if I’m talking with a less than trustworthy person just be hearing conversations and body reactions and micro expressions. After almost a decade my job habits are now my own habits.
In that point sometimes what hides behind my smile is the fact that I know I’m talking with someone who doesn’t deserve a smile, but the show must go on as they say.

Anyway be it more or less sincere, I do try to smile because my life is good after all. Also being sincerely nice to others often opens more doors than being a asshole, I learned that from experience.