Energy and Age
I accept that age is linked with less energy.
As a kid, you have grown seeing your grandparents treated "specially" more often as though they are disabled. Your mind has registered that if someone's old, he will have no energy.
Probably, because of this we always love to live in "sweet 25". We know that once we grow, we will also see similar fate as we had seen elders in our childhood. I know, You had wished if you could return to your 25!
And dear friend, you can return to your twenty-five - the one that comes with the feelings of ever youth, energetic, enthusiastic, etc. If you want to know, then open the eyes of your mind. Your mind is the Ubiquitous owner of your body. What your mind says is what your body is.
Your mind orders that your body is growing old, and your body shows the symptoms of aging. Let your mind "order" that you are ever young, your body believes it. One word of caution here. Your body obeys your mind's order only when it's beyond doubt!
Got it? Practice it!