this is kind of the backwards version of "13 Going on 30".

One morning you wake up, and you're back in your childhood bedroom. When you look into a mirror, you're met with the reflection of your twelve year old self. You have gone back in time, but you remember everything that you know at whatever age you are now. So:

What is your first reaction?
How do you treat your family and friends?
What do you do differently with your life?