Making someone else's day can really make YOUR day.
I love hearing those words out of someone's mouth:
"You just made my day!"
Love it. Love it. Love it.
So put your neck out there. Try it. Compliment a stranger, help someone parallel park...maybe today, maybe tomorrow.
Also, in researching that phrase quickly, I found this website. It's the happy opposite of FML. It's IMMD -- http://itmademyday.com/