Not my note.
It's so easy to rip people down. Pump someone's tires. It means way more than you can imagine.
Long before I was a dad, I once told a dad I saw in a retail store "you're a great dad!" after being in an adjacent aisle and hearing him interact with his kid. He was clearly offput by the input. That was the only thing I said to him; hopefully it had a net positive impact.