Sim is both hyper and chill. His temperament seems to mimic mine. If I want to go for a run, he is right there beside me. If I want to veg, he's more than happy to take a nap; although, his favorite pastime will always be chewing. Sim can be stubborn, but I have never known a more loving dog. He gets along with every living thing, which can be a problem if that living thing is a skunk. TL;DR: he's the best.