Team sports aren't my thing. I find it easier to pick something up if I can do it at my own speed. And you don't need a partner to go running you don't need a particular place like in tennis just a pair of trainers.
In the beginning we had a great deal of freedom and Jerry wrote completely out of his imagination - very very freely. We even had no editorial supervision to speak of because they were in such a rush to get the thing in before deadline. But later on we were restricted.