You asked the question. Yes, you are crazy unless your child is differently abled and cannot walk. If your child is a normal kid who likes to get his or her way, time for him or her to learn the hard facts of life.
Instead of using a stroller, walk at home to build up endurance. Take breaks at WDW. Go early before the crowds get awful and take a break around lunchtime and hit the pool. Sit down and watch the people go by while munching on an ice cream or other cool treat. Walk slower. Wear comfortable shoes.
If the whining begins, head to the hotel and take a rest.