Walked past a woman in Trader Joe's today. She had a baby strapped to her chest, wailing inconsolably. The woman looked quite stressed.
I said, "Hang in there, you're doing great!" She smiled and said thanks.
Walked past her in the parking lot later, and she said that I "totally made her day" and that "it means a lot to hear encouragement rather than get those side-eye glances."
It's totally free to be nice to other people, and it can mean so much to them! And it made my day as well. 10 out of 10, would do it again.