For Me I learned to be gratefully in workplace from my colleague who is being thankfully even after a very small conversation and sometimes even she helps me after that, is the one who says "Thank you".
When I go to visit to her place after saying goodbye she will say thank you.
From her I have learned to be gratefully in workplace and non working place.
So in order to inspire workers expressing gratitude in the workplace is better to have gratefully photos or gratefully messages around workplace or offices.
This is the sample of photo.