Mood. work

If you are in a bad mood, smile. "Research has shown that if people smile, even if it's forcefully and not supported by an emotional experience at first, their mood will improve," says Von Stumm. "Also, smiling will make you more likable, and smiling will make your voice sound more appealing."

If you are in a good mood, work. "Although the findings on the relationship between mood and cognitive performance are to date fragmentary and somewhat inconsistent, preliminary empirical evidence suggests that our brains work faster at times when we experience more positive affect. So next time you are in high spirits, don't head to the park or pub with your friends, but tackle that work project or textbook that usually seems too hard to take on."

If you go from high to low in minutes, stop and take a break. "Frequent and extreme mood swings are early signs for psychological imbalance that often results from poor sleep due to stress," notes Von Stumm. "It's easier said than done, but when you notice your mood becoming unstable, take a step back, try to identify the source of stress, and eliminate it. Sometimes it's enough to become aware that a situation is stressful for us to find our balance again."