Who am I?

So I've been reminded lately that we are a culmination of our past experiences.  Good and bad.  We go through life in reality living in the moment because that's just the way it works.  But when we get to a certain point in our lives, we look back and can recognize those experiences, people, trials and events that have helped shape who we are as individuals.

I look back and see many things.  Past experiences with friends, girlfriends, family.  How have these things shaped my attitudes, habits and personality?  I'd like to think I've taken all the positive aspects from my past but I know that's not always the case.  This past year or so has been cause for significant reflection on why I am where I am now.

There are things that I would definitely go back and change.  But at the same time, would that make me a different person than I am today?  Just food for thought.  There's always that 'what if' scenario.  Unfortunately we don't exactly get that chance.  To go back and take the other path.

So that brings me to my question...If you could go back and do / try something that you passed up the opportunity to do, what would it be?  And also, If there is one thing you could go back and not do that you regret, what would that be?