If you could go back in time, and change something, what would you do?

There are many things in my life that didn't turn out exactly perfectly, and it's tempting to say that I'd go back to change one of them. However, we just don't fully understand how one thing affects another, and I wouldn't want to take the chance of impacting something else wonderful in my life by getting rid of something that wasn't so great. I think that our lives are formed by the total of our experiences and to upset that balance by going back to change something might make our worlds entirely different on the other end of the change. So even though my life has not been perfect (not by a longshot), I would not change a thing.