One of my first ( and [quite luckily] only) experiences with pain/loss was when I was 7 and my goldfish died. I know, this doesn't really seem like a very major loss, but for me, it was. I cried several times, and spent several days feeling sad. It was my first real experience with loss.
I had gotten my fish from a magician named Amazing Ken who was at my birthday party. I had gotten many goldfish from him in the past birthdays, but this one I felt was special. I named him Harry. Amazing Ken's birthday goldfish I knew were not meant to last long, so when he died a month later, I wasn't terribly surprised. I had been coming back from vacation with my family when he died. I looked at him and immediately, with my 7 year old knowledge of fish death-causes, determined that he died of a fish stroke. I was extremely sad.
Growing up, everyone experiences loss in someway or another, whether it is a small goldfish or a family member. Though many different types of things can be lost in life, there is one thing that I know for certain everyone loses- their innocence. I believe that when my fish died, a little piece of my innocence died. That was the first time I realized that things actually do die; before that incident, I though that death was just a made up thing used to scare little kids. An experience with loss, while growing up, I believe is a very important experience to have.