Working as the 'face' of the country begs you to be the image of what you represent: your country. I smile and sometimes pretend to smile whole day depending on the situation or the mood I was having at that time. And of course it also depends on who came to my desk or met along the working hours. Smile helped me reduce stress, and I found that smiling make other people feel cared or respected or better yet, smiling changes moods. I used to meet people who came to me brooding, or act like shit, maybe a bit tired from long queue or just look down on me/us (the civil servant). When they come, I just give them smiles and I noticed things were changing. I leave it for you to imagine the next thing happened after that. By the way, smiles should be accompanied by greetings and what's best is to be polite. Respect. You earned your respect when you respect others.