I once read somewhere (okay it was a Sidney Sheldon novel) that the word 'IF' is a two letter word for futility. I've always remembered that line and when I think about it the next thing I hear in my head are the words "two roads diverged in a wood, and I, took the road less traveled by, and that has made all the difference". Gotta love Robert Frost (who would ever use the word 'gotta' in the same sentence as Robert Frost?!). It's human nature to wonder what life would be if the choices and decisions you made were different.
I think about it now and again, but less as I get older. I usually think about it when that nagging word 'if' comes up in conversation. It's almost more scary to me rather than exciting to think how different my life would be. You can look at almost anything in any way and if it had been even slightly modified the place you are sitting right now would be different. You can break it down to a minute detail or a significant occurence that would have altered your world--and the people in it.
I tend to think more about choices I make now and what will be--more than I think back about what might have been...that is, until it comes up again in conversation. IF it does. hahaha : )