Why won't my fat lard of a sister exercise?

im pretty and model and my sister is fat and ugly and in denial about it. To get her to exercise I put 500 donuts and a Micky d's coupon in a wagon and roll it down a hill and make her chase it. She, instead, rolls down the hill and gets free donuts without the exercise. She was this huge boil with a hair on it on her chin. Hoe can i get her to look in a mirror and realize the ogre she is?