Complex sentence: His hobbies include playing and listening to music and reading fiction, but his favorite thing to do was go on long walks with his dogs when he had them because it was the best thing for his head and soul.
Split into simpler sentences: His hobbies include playing and listening to music and reading fiction. However, his absolute favorite thing to do was go on long walks with his dogs when he had them because it was the best thing for his head and soul.