Honestly, I wish I had a big elaborate explanation why I believe in reincarnation.
The truth is....it's really the only thing that ever made sense to me.
I remember from a young age feeling as though my body is simply my home for now.
I read a book in my mid-teens called Many Lives, Many Masters. It was basically about a woman that had suffered from so much anxiety in her everyday life that she sought help. Throughout the course of the book past life regression happens and they discover that a lot of her anxieties stem from things that happened to her in various previous lives. I think they had documented 80-some previous lives. Book was supposedly written by her doctor, and supposed to be based on true events. It was a very interesting read. It was said there that the soul is reborn for as many lifetimes as it takes to learn all there is it needs to know, and when it is finished it becomes a guide for other souls on their journeys. I'd definately reccommend it. :)