It sounds like a trip to the veterinarian is in order, Rob. Your vet will be able to determine if the change in your dog's activity level is due to a health issue or if it’s simply part of the aging process. The food you feed him plays an important role in your pet's health. If you’re feeding him a diet of only boiled chicken, your dog is likely lacking nutrients that he needs to remain fit and healthy in his golden years. We generally recommend a high-quality commercial diet─it’s a very convenient way for pet parents to provide excellent nutrition to their pets. However, if you prefer to feed your dog a homemade diet, it’s important you use a recipe that has been formulated by a veterinary nutritionist. This will ensure that all of your dog's nutritional needs are met, and if chicken seems to be important to his health, it can be used as a primary ingredient in these recipes. Please also be sure to consult your veterinarian prior to making any changes in your dog's diet.
Exercise also plays an important role in your dog’s energy level. Elderly dogs may require less exercise, but it’s still important that they remain fit and active in order to help maintain their good health. A sedentary lifestyle can make your pet more prone to weight gain and therefore, more lethargic. It’s also important to remember that overweight pets are more likely to develop diseases such as diabetes. Therefore, your dog should remain somewhat active. We would recommend discussing a proper amount of exercise with your veterinarian, who knows your pet and his history and will be best able to give you specific exercise recommendations.