I have a male rat, a little over a year old. He's sweet, playful, and cuddly, but has been getting quite overweight. This is due to his extreme aversion to his wheel (I've bought him 4 different ones, and he's hated all of them) and his ball (I think he is scared of it-- I put him in it, and he defecates immediately, which he doesn't do outside of his cage unless he is upset). Though his chubbiness makes him all the cuter, it is obviously a health concern. I feed him moderate amounts of food and limit the treats I give him. I let him run around for a few hours a day, but clearly this isn't enough physical activity for him. How do I get him to take to his wheel and ball? And are there any other alternative exercise methods you'd recommend? (I've heard you can take rats for walks, but I live in the upper Midwest, and it's getting a bit cold and snowy for that). Any advice?