You can only burn for so long. As soon as you stop growing you begin to fade, it is extremely difficult to stop fading and reenergize once you have begun to fade, but it is possible.
A way to stop your fading is by asking questions. Life, in essence is the constant search for what makes you happy. What makes you happy one moment may not another. It is extremely illusion.
Every day you have to realize you get reborn to experience life in a new way within tour great saga known as life. This mindset will keep you youthful and your body will respond to it as much as it can. You just have to experience every day as new after you are finished with them to your own standard. They serve a purpose, these memories, but once their purpose has been served let them go, do not dwell on them and make them your future. By not participating in others dwellings of the past, you will see the positives you create in your life, as well as the lives of those around you.