Allow me to enlighten you. There comes a point in life when you're this size that nerve endings have been feeling "pain" for such an extended period of time, that the brain just readjusts to the new "normal."  They are in constant pain, but in order for their brain to function without them going crazy, their brains "trick" themselves into thinking constant pain is normal. It's similar to what prisoners-of-war did; they were always starving, but since starving was their new "normal," their brains mentally readjusted to function around the starvation and not feel the dull ache at all times. The brain is an amazing thing, really.