Getting out of the wrong side of the bed; feeling blue; everything looking grey;having a bad day; all these could be just your imagination!
There's an actual science behind why a bad day happens, according to Peter J. Bentley, Ph.D., author of "Why Sh*t Happens: The Science of a Really Bad Day."
"Those who have a negative attitude are more likely to endow normal little mishaps with some mystical significance," The New York Daily News quoted Bentley as telling Lifehacker.com.
Bentley's suggestion: Describe what you feel in three words. Then move on.
Simply condensing one's feelings into a word or three can cut back on the effect of negative emotions.
Rethink the events, and try to find what good came out of it.
Bear in mind that whatever happened five minutes ago does not have any bearing on what will happen in the next five minutes.
And of course, talking to a friend always helps - but be careful not to overturn your anger and frustration onto them.