I remember one, though no idea what it was called about this old man that was grumpy and never smiled at anyone. The local children were frightened of him, but this one little boy used to smile at him whenever he saw the man.
The man never smiled back to start with, but then started to and it turned out he was just lonely and this one little boy just smiling at him cheered him up, then he was happy and started smiling at everyone too.
I wasn’t that old when I read it and it’s always stuck with me, that sometimes just someone smiling or acknowledging someone can make a difference to them.