One time my mother told me, "What your father and I love about you is your quirky sense of humor."
I'd never thought much about my comedic style (?), yet it was great to learn it was an attribute a mother- and father!- could love. I treasure her remark.
It takes little to make another person's day. Ignore them when they greet you in the morning. You know what his or her day will be.
Acknowledge him or her with a warm "Good morning!", and you've done your part for civility and good mental health.
The most interesting thing about me is that I was a US Army motion picture photographer between 1970-1972. I was stationed in Kaiserslautern, Germany. My job took me all around Europe. It was great fun!