Spot is around 4 months and a half old. Spot keeps going into his litter box to roll around in and sometimes, just sit in there. No matter how many times I tried to stop him, he does it again and again. I clean out his stool often so he doesn't actually roll around in his own poop, but it's still kind of gross to go in it and play around and to just sit in there. I don't know how to get him to stop going in it other than to actually use it for its purpose. Any advice?