As to the theory that PE teaches kids to enjoy exercise, I'd have to say that I found kick-ball the last exercise done in school that might have been termed enjoyable. Everything subsequent to that involved Nazi gym teachers and resulted in my avoiding those activities for the next 40 years. (Yes, it does show. Thanks for asking.)
I bet a good percentage of the people reading this comment would agree that school PE was the last thing that taught us exercise was fun. You are among friends - as you know, people who read slashdot, we were usually the last people picked for the kickball team. And even when I wasn't - I still hated PE.