I know what you mean. I paid for swimming lessons for 3 years in a row, but at the last minute, my son refused to touch the water. While at Disney, he just jumped right into the pool, even tried swimming underwater. He bobbed up, smiled at me and said "I guess it's that Disney Magic Mom, I like swimming now". He's a fish now, and you can't keep him out of the water.
One of my daughters has Aspergers, and over-stimulation is a real problem. I was really worried about going to WDW the first time. It turned out to be the best time in her life. She positively bloomed while we were there. There is no way to discribe the change in her while there, but all I can say is to quote my son "It must be that Disney Magic"
Now I just have to figure out how we can get back down there!