Smiles are good, Grumpy is Banned
If you don't care about what you do, don't do it!, don't subject your customers to anything other than "I'm awesome, this place rocks and we're here to enjoy ourselves"!
So if you turn up to work all cranky and grumpy one day and your boss sends you home, that's a good business decision. Take a mental health day and come back smiling the next :)
What do you do to help your staff maintain a positive outlook? How do you encourage your people to leave their personal issues at home and come to work professional, positive and ready to GO!?