Pain: to lengthen the lives of individuals by keeping them away from danger.
Amygdaloid: Part of the brain that senses threat and danger, to prepare your body for fight-or-flight situation.
Amazing how our body system works to protect us. Even more amazing that the things which harms us actually do us more good than expected in helping to keep us alive.
Hence, don't be afraid of the pain, it'll help you grow.