Thanks so much, Lucky Rescue. for the advice and the links.
So this means that aside from a few minutes of play time allowed after he is, as you say, "empty", that he really needs to be on the leash or in his crate. He had been doing so well that I had thought I could let him play or be out without a lease. I am not fast enough to catch him when we are playing and I see him start to sniff ( he's a fast one!!).
When I put the lease on him is it okay to keep him with me or do I have to fasten him to a stationary spot? What do I do if he constantly tries to eat his leash?