I am a coffee shop waiter, every day I have to smile when serving customers and I like that because smiling can make someone happy. 
yeah even if they are sometimes getting RUDE and MEAN to us, What we must do is Smile and let them feel your Love. i work at tourism as a waiter,everyday when i meet with alot of passenger with big smile,,big job with big pressure but i need to smile every single time ,thans very important 
So you are almost the same with the person above? service Man for the clients/costumers .