Toby is 20 weeks old. He does sit VERY well but for some reason he seems to slide even on carpet. Its like he pushes with his legs as he is sitting. He can sit straight but chooses to slouch a lot. Is there any way to get him to sit like he is in the ring and not slouch or push off. At our training sessions the floor is concrete and slick so Toby never sits still, he slides.