We have all encountered failure, be it failing a final exam, or a job interview. We're told that overcoming difficult obstacles will make a future success much sweeter.

But new research shows that initial failure can lead people to underestimate how good it would feel to succeed.

• "The grass is always greener on the other side" suggests that people spend much of their time longing for things they don't have.
• In Aesop's fable of "The Fox and the Grapes", the fox walked away from the grapes he desired because he could not reach it, concluding that the grapes were probably sour anyway. This tale teaches that failure can make future success appear less attractive.

In a study, people who see grass as greener on the other side predict higher happiness with future success. Participants that reacted like Aesop's fox would try to distance themselves from failure. It suggests that initial failure made people underestimate how good it would feel to succeed.

Named after "The Fox and the Grapes", the sour-grape effect is a systematic tendency to downplay the value of unattainable goals and rewards. We underestimate our future happiness because we don't always know what we want, and adjust our desires to what appears within reach.

People will rather devalue a goal than devalue the self. It means that people could miss out on the chance to try again because what once seemed impossible might now be within reach.