Catch me if you can

I wrote a page-long post today, then erased it all. It was just a bit too gloomy and sad - while I wanted to end the day on a happy note.
So if you, just like me, are feeling a bit down, then maybe this will do the trick.

CATCH THAT SMILE
Smiling is infectious, you catch it like the flu.
When someone smiled at me today, I started smiling too!
I passed around the corner and someone saw my grin.
When he smiled, I realized I'd passed it on to him!
I thought about that smile and appreciated its worth.
A single smile, just like mine, could travel round the earth!
So if you feel a smile begin, don't leave it undetected.
Let's start an epidemic quick, and get the world infected!