It will be challenging initially, but he will get used to it. When the animal stands in front of the pen and looks at it, throw him some food or his favorite toy. If the animal has entered the cage, it should only be rewarded. He must be praised, petted, and fed some of his favorite treats. Food is given only when the animal is inside and sits comfortably in the puppy play pen. This way, he will understand that he did what he needed to do and learn the exercise and execute the command again.