Yes the answer to old tough meat of any kind of meat: LONG SLOW COOKING, especially adding acid: tomato, citrus, vinegar etc. But that chicken I would return to the store.
Just for laughs, when I was in college and learning to cook, we tried to cook a chicken that was pretty tough to begin with. With half an idea in my head that boiling was the way to deal with it, we boiled it. After an hour, it was even tougher, so we turned the heat way up and let it boil hard. Boiled all the liquid off. Added more boiling water. After boiling it for 4 hours at the highest heat possible replacing the water as needed, we finally threw the whole thing out. Tougher than an old tire.I remember that and laugh every time I poach chicken.