The best investment you can make in creating a positive workplace is to catch people doing things right. Whether it's your boss, a co-worker, a direct report, or the janitor, catch'em doing something right and thank them.
When people are shown appreciation it literally makes them "feel" good according to The Carrot Principle, a book about how praise not only improves production but actually makes people healthier.
And praise has an echo effect. If you praise a person and others see the praise being given studies show that hey get a good feeling too. Catching people doing things right on a regular basis is the best way to create an "attitude of gratitude" in your workplace. More gets done, people are happier, and increasingly studies are showing that positive organizations are more profitable.