How would you maintain a smile on your face all along a hard day?

This question is to ask you to know about your behavior and impulsiveness towards your work. Here is an example of an answer to this question:

I used to maintain my smile the entire day whether or not that day, I had a pressure of my work. My enthusiasm for my work always allows me to smile in tough situations. Hard days are the part of life, whether professional or personal; we all should be ready for those.