So I'm walking my dog on the beach when an obeast and her fat dog appears... and we have the same breed of dog, golden retrievers.  My dog is normal sized and runs around like mad, while her dog is fat, with a flat back, and it can't keep up with my dog who just wants to play.  So the fattie asks me "How do you keep your dog so thin?"  I look her in the eye and say, "by not over feeding her.  You have to weigh her food and if you give her treats, you must give her less kibble."  She reees "but I walk her every day,"  and I reply "well your dog is fat, you are killing it with food".  I leave her staring at me, slack jawed.