It's a question that most of us have thought about at some point. While it's not a good idea to live regretting things you did or didn't do, it's always interesting to hear what other people would change about their lives if they had the chance. Photographer Derek Kennedy went around Dublin for the day asking people what would they change if they could.
Conor Doyle, Maynooth, 21
I'd change the decision to come home and I would still be in San Francisco working in the media.
Charlotte Dubial, 22, Seattle
I would go back and learn how to read music and instead of going to school straight away I would try to make it on Broadway.
Kevin Fogarty, 26, Kilbarrack
I wish I could of said goodbye to my granda Kevin Fogarty, and I wish he spent my nanny's lotto money on them winning numbers instead of putting it on a horse!
Tony McGuire, 71, Walkinstown
I wish I never opened a business, I lost an awful lot lot of money!
Aisling Reina, Ranelagh, 21
One thing about myself, I wish I could be more confident.