Laugh.

We’re all drawn to people with a sense of humor. Humor is a great way to release tension and shake a bad mood. It can also make the workday more fun—so long as the humor is appropriate, not offensive to others, and doesn’t interfere with work.
• Use humor to lighten up a difficult situation.
• Look for opportunities to laugh with co-workers. Start a joke-of-the-month contest. Clip and post cartoons that make you laugh.
• Buy a funny card for a co-worker.
• Don’t be afraid to laugh at yourself.