I'm not sure why you wouldn't want this? Must suck being old and tired all the time. I'll take youthfulness over that any day.
At age 52 I can honestly say I don't feel more tired or generally any worse in any way than I did when I was 16. My eyes are about the only thing that has noticeably aged. I'm a bit far sighted at this point
Do you still exercise? I personally think that the biggest part of feeling more tired with aging is that people just stop exercising. Not exercising less, just completely stopping, because you get caught in a cycle of being too tired from work/commuting to exercise, and having less energy due to a lack of exercise.