If you could go back to your past and change something what would it be with the time limit of 3 days?

Okay I’m asking this question since I know I should give up MY past and get over it, but I’m not one of those guys that just FORGETS about it. It’s still in my mind and I keep thinking of all of the things I should have done…or things I shouldn’t have….When ever I think of the past I always think of my life being a mess. When I was in 2nd-4th grade I was always depressed and quiet. I did have my friends, but they didn’t except me because of the depression. But hey I still have them now. What I’m saying is that I would change that. To uhm…being more positive and still have my quiet inside me. I would change many things in the 3 days if it was enough time….But I know it would affect on how I live today. But how would you guys change your past. How do you think it would change who you are now?