What thing is there you don’t want now that you miss if you could not have it?

Over the years I have heard people speak of things they miss having or now can’t have that they didn’t want when they had the chance to get it or do it. Sometimes that thing was the ability to play the piano that they missed after an accident that took away that ability. Sometimes it was a house they inherited or a boat handed down to them that they didn’t want until it was gone. At times it was the chance to go to a particular college on a scholarship that wasn’t used for whatever reason. What do you have that you wish you could have back that you did not make use of when you had it?