I got my English bulldog puppy last week. He is 4 month's old and we decided to take him out for a walk. As soon as we put on his leash he just sat there and wouldn't move. We had to carry him and this is a 20lb puppy so it was quite a workout. I would put him down and he would just stay and not move a paw. I don't think his previous owner ever put him on a leash and I don't know what to do to brake this bad habit. Do you guys have any suggestions ?