To my 6-year old self: Don't be a quitter when it comes to swim lessons. Knowing how to do more than just dog paddle might come in handy one day. (psst - good call on quitting gymnastics though; 23 years later you are still as klutzy as ever).
To my middle school self: Stop obsessing about your terrible bowl cut. It is hair. It will grow back. Instead, turn your energy to something fun and creative. Learn Irish dancing, how to create pottery, photography - SOMETHING. Otherwise, 17 years later you will find yourself wishing you had something different to talk about besides swimbikerun.
To my high school self: Be nicer to your parents. Yes, they are rather strict. And yes, you would still behave perfectly without all of the extra rules - but those rules gave them peace of mind. Also, learn how to embrace athletic challenges and competitions - they are fun and not meant to cause so much angst. Oh, and put some effort into focusing and actually doing your best during practices and races - you'll probably exceed all of your expectations.
To my college self: Don't float through life during college - seize every opportunity you are presented with and always search for more. Take advantage of all the cool programs at school - go skiing, kayaking, snowboarding, hiking, camping (OK, well maybe not camping - you hate camping), take a dance class, go on community service trips to foreign countries. Once you get out of school and enter the real world, this stuff costs money and takes up time you suddenly don't have. Oh, and quit the diving team - join the swim team instead (see above note on gymnastics and klutziness).
To my study abroad self: You are going to France. To live in a medieval town. In the French Alps. Get the hell out of the student bars and go see some French stuff! Go ski. Go biking. Explore. Have your host mother teach you how to cook some of those amazing meals that just pop out of her oven. The bars and alcohol will be waiting for you when you turn 21 back in the US (and the novelty of barhopping will wear off shortly thereafter).
To my post-college self: The defense contracting industry is not for you. Don't wait 5 years to finally come to this realization. Set goals. Make a plan. Don't wait 4 years to go back to grad school. Master the art of non-procrastination before you start grad school - otherwise, it will be 2.5 years of very little sleep. Make an effort to show your friends and family you care about them - life is busy and gets in the way, but that's a shoddy excuse. Marriage is about compromise - as nice as your husband is, you are not going to get your way every time. Get over it. Mac and cheese is not a food group. PS - triathlon is expensive. You might want to consider getting a second job to support your growing habit.
To my current self: Stop procrastinating on taking that photography class or Irish dance lesson - do it now. Embrace each day and never forget how lucky you are to be living your life the way you are. Take responsibility for your actions, reactions, and future - only you can influence and ultimately decide those outcomes. And stop comparing yourself to others - circumstances and abilities differ and no two people are the same.
One more thing - go to bed earlier. I'm going to take my own advice and sign off.