Moods are dynamic, so the conditions are..
When you become the new person, in different scenarios with new people, sometimes you yourself do not know..
You would meet to someone for 2 minutes, or for 2 hours, or for 2 days, and that each person has the capacity to influence you or change you in a big way..
Your simple smile can affect the other person in a very positive way, it may relieve them from anxiety, or it may make yourself approachable to them, so just keep smiling..
These are some of my thoughts, so just penned down these to share with you all..