When Henri is being stubborn, I just give the lease a light tug (hard enough so he feels it but not drag/hurt him) and say in a happy sing-song voice "Come on! Let's go!". If that doesn't work, I just start walking ahead and say "Ok, I'm leaving you here then" in a serious voice and that will usually get him going.
I don't know if this will be any use to you, good luck!
