There are several different approaches to take with this. The main idea in personification is one whereby human characteristics are given to animals or objects to bring a greater level of connection between authorial intent and reader understanding. I always like to think of personification as a form of visualization. In the setting with the cat sitting, I think we can go with different takes. If there is a mood or feeling of nervousness or uneasiness, "A cat sitting in nervousness, unable to relax, but unable to sleep." In this personification, the cat is being linked to nervousness, a distinct feeling that humans can understand and experience. It is a human reaction that animals also experience, but one that humans primarily understand. Another example would be, "a cat siting in presumptive judgment of its surroundings." Here, the cat is being given the power to judge or assess its conditions, almost like a judge or some type of adjudicator. Finally, if we wanted to convey a sense of sadness or forlornness, "a cat sitting in wait for absolution." This can take the human experience, connect it to the cat, which in turn forges a stronger connection with the human reader.