Is happiness a duty?

There is no duty we so much underrate as the duty of being happy. By being happy we sow anonymous benefits on the world. Robert Louise Stevenson

I like the idea that by being happy we spread happiness. I'm not fond, however of happiness being a duty. Sometimes we just aren't happy, and there is nothing anyone can do about it.

I am hoping to smile till my face hurts over the next couple weeks, enjoying sun and fun in Mexico. This time last year we were recovering from a snow storm.

Going from wet weather to sun should make me smile don't you think?