I'm sure your 'to do' list runs to 2 pages long, right? Well, here's another bulletpoint to add to that list - but it's one you'll get an immediate return on.
SMILE! Yep - simple as that!
By wearing a smile, you instantly influence the people and atmosphere around you. So, before you walk into that meeting, that presentation, or just to the water cooler, put on a happy face.
I'll bet you get it back ten-fold. :-)