Not in monetary value, either. I mean, how much is it worth? Smile ... now. How does that make you feel? If you did it whole-heartedly, it made you feel better than you felt a few seconds ago. Seriously. If you didn't do it whole-heartedly, then fake it. Do it again. Smile for someone else. Make their day. Make them smile ... or stand up a bit taller ... or at least feel a bit better.
For the value, it's the best thing you can do today. Smile!
Smile at kids. Smile at adults. Smile at co-workers. Smile at strangers. Smile at your neighbors. Do it. Genuinely ... do ... it! Make someone else's day. Make your own.
It's your attitude. As they say, "Fake it, until it's for real!"
:)