On the off chance you weren't convinced by last week's posts that gratitude is really important in a professional setting, I recommend you read Kevin Eikenberry's very readable, very eloquent column on gratitude and leadership.
Eikenberry, a leadership consultant, stresses:
Great leaders show their gratitude freely and genuinely. If you wanted to learn something about marketing it is here - be gracious. Good marketers know that saying thank and meaning it is good business. If you wanted a motivational idea, giving thanks can be a powerful motivator to both the giver and receiver.
Check out the whole column. It may inspire you further.