Well, when I was a little child of 11, I began to be vegetarian. My mother was afraid it may be harmful for my health, however the doctor respected my choise and took care not to give me even a medicine that might contain some animal substance.
At that time I was pagan and worshipped the Sun and Nature. My idea was that all beings were good (animals, plants), but humans were evil. So, when my mother insisted that I should eat meat, I always replied, "I'll try to eat if you let me eat the butcher first, why would I eat an innocent cow, and let the butcher alive? He would kill me if I were a cow!"
At that time I had my own garden, several palms trees b/c I sympathised with African cannibals, and Sunflowers b/c The Sun would protect my garden in case of a storm, and he wouldn't let his flower to be destroyed.
Now that I have known Hashem, I wouldn't eat human meat. But if it is a life death situation and Torah commands it for Pikuach Nefesh.......May HaShem never put me in that situation.