I'm guessing that we've all been guilty of not giving appreciation when we should. From big things like forgetting to say thanks to a friend that took time out of their day to help us with a trouble of our own to not passing along our gratitude to the chef that made us the best steak that we've eaten in quite awhile.
The thing with appreciation is that it doesn't cost much. It costs a few seconds of your time in most cases. In some cases it may require us to swallow our pride and say, "Thanks. I couldn't have done it without you."
But the reward is monumental. If someone has ever expressed true appreciation to you for something that you've done, you know what I mean. It's encouraging to hear that you've done something that made someone else feel good. It has the power to change someone's day or even their week.
If done correctly, appreciation costs little and gives much back to the world. Tell someone thanks today. And most of all, mean it.