When you age your metabolism automatically start slowing down its process. A slower metabolism makes us fat as more fat starts storing in our body. Having a fatty body is another factor that makes you look old. However, you can keep your metabolism healthy forever by many different ways. The best possible method to keep metabolism healthy is doing cardiovascular activities in the morning. Morning is the most ideal time for this as while sleeping we use most of the carbohydrates in our body and when we wake up and do cardio exercises, our body burn fat when it cannot find carbohydrates to burn.