It will do them some good. Spend some time just being with them petting, brushing, or talking. It can go a long way toward improving attitude. Third, watch for injuries. A change in attitude, appetite, or gait, can be an indicator.
Check joints for range of motion or swelling.
Rest them or see a veterinarian as needed. Dogs will need more calories when training and when the weather turns cold. Increase the amount of feed and increase the fat content. Making sure that your animals are adequately hydrated is just as important. Soaking food and baiting water are two important ways to achieve this goal.