Those who decided to have plastic surgery are 'happier' than those who thought about it but decided not to go ahead. Would be interesting to see if a similar effect shows up in other large decisions - eg, people who decided not to buy a house v those who took on the debt; people who decided not to move overseas v those who took the plunge.
In other words, this may have nothing to do with plastic surgery and may reflect a deeper underlying source of (un)happiness.
Me personally, I have just one regret in life: that I didn't rob a bank when I had the chance.
[EDIT TO ADD]
When I was fifteen, I headed in to my local bank to withdraw some cash. Troublingly, my 'local' branch was close to where I was at boarding school, some 100 miles from the branch where my account was established - and it transpired that the signature on my account was still my mother. We'd not updated it since the account was opened nearly ten years earlier.
Maybe they felt sorry for the poor boarding school kid with no money. I suspect I hammed that up a little. Because rather than referring me back to the original branch, the customer service representative headed out the back to see what she could do. For a LONG time.
About fifteen minutes in to the wait, I leant over her desk and noticed, in among the paperclips, a 20 cent piece (this is Australia). I looked around - cameras, probably, but nobody watching.
And so my brain starts ticking - surely I could casually reach out, grab that coin, and pocket it without being noticed. Surely she wouldn't notice on her return - if she even knew the 20c was there. It was a risk ... but for the rest of my life, I'd be able to tell people I robbed a bank!
I probably spent another fifteen minutes pondering the decision. Which was too long - she returned, and the opportunity was lost.
For what it's worth, I was able to withdraw funds legally. She'd had a great conversation with a teller at the originating branch, who it turned out knew my father (everybody does). Based on descriptions of my father, and comparisons to me, my rep felt confident I was indeed who I said I was and changed the signature on the account from my mother to myself.
Now THAT'S a great customer service story as well. Or a tale of social engineering being the weakest link in any security plans.
But for me, nearly twenty years later, it's just the story about the day I could've robbed a bank ... and didn't.