Nazanin Zaghari-Ratcliffe beamed with joy as she stepped off the plane and hugged her daughter Gabriella. 

Six years ago, Nazanin was arrested in Iran. She was accused of plotting to overthrow the Iranian government and imprisoned. Today, Nazanin and another British-Iranian prisoner, Anoosheh Ashoori, are finally back in the UK. 

Waiting alongside Gabriella was Nazanin's husband, Richard Ratcliffe. "You can narrate our story as a love story," Ratcliffe told a journalist last year. "It is, like all ordinary families are." 

Now, they want to be a "normal family" again. After years in prison, Nazanin's first act of freedom will not be going on a lavish holiday or eating an expensive meal. Instead, she will drink a cup of tea and look at the toys her daughter has picked out. 

Millions of people worldwide spend years pursuing extraordinary experiences, a successful career and the perfect family. But some think being average could be the real key to happiness. 

The author Catherine Gray was once a successful magazine editor. But the endless parties and free yoga retreats never satisfied her. 

"I was always wanting, striving, seeking the extraordinary, but when I was in the extraordinary, I wanted it to be more extraordinary," she recalls in her book The Unexpected Joy of the Ordinary. When Gray found happiness again, it was in the "forgotten joy" of normal life.

Essayist Nassim Nicholas Taleb agrees. He believes that to be "a well functioning human" you must be "mediocre" - a mediocre runner, mediocre chess player and mediocre martial artist. 

Of course, extraordinary moments can be worthwhile. One 2014 study found that extraordinary experiences strongly contribute to happiness. But for the Ratcliffes, returning to normal is the priority. 

Yes: If we constantly compare ourselves to others, especially the famous and the wealthy, we will never be satisfied. The key to happiness is appreciating the good things we already have. 

No: Many people are bored and frustrated with their ordinary lives. The millions who seek fame, fortune and celebrity each year are clear proof. Success is far from overrated. 

Or... What makes someone's life "ordinary" or "extraordinary" is entirely subjective. Moreover, everyone is different - no two people will find happiness in the same way.