If a pretty poster and a cute saying are all it takes to motivate you, you probably have a very easy job. The kind robots will be doing soon.
If you're not a part of the solution, there's good money to be made in prolonging the problem.
Sometimes the best solution to morale problems is just to fire all of the unhappy people.
Because you've given so much of yourself to the company that you don't have anything left we can use.