He's only 4 years old and he enjoys playing, he's just really fat anyway. It's unfortunate but there's not a ton I can do. He's happy for now.
He's a Labrador Retriever, so I'm not surprised he is overweight. Some dogs, like people, are just built with a little extra. As long as he is healthy and happy, there is nothing wrong with him being a bit of a chunky monkey. lol