Well...Since you brought it up David or whoever posted this. Okay, I've never heard of it but I did do a google search and found this link which sounds informative, from ezine:
http://ezinearticles.com/?Youthing,-Not-Aging&id=114902

The latter of the article about activities for youthing ring so true, I do this anyway. I will NOT CLAIM OLD AGE. I refuse.

I note this article focuses on the psychological components of youthing. This will of course be very different for each individual.

Concerning physiological aging, there's been found a few activities (of passivities!) that has been scientifically found to meaningfully reduce the rate of aging:

1. Choosing your parents well (Genetic make-up)
2. Restricting nutrients (to about 60-70% of RDA) OR eating only every second day (These 2 approaches had about the same effect, increasing life expectancy by more than one third)
3. Being, and remaining, married (This had much more effect on men than on women)
4. Not smoking of course
5. And numerous other smaller factors.

The exact rationale of each of these is of course debatable but I give them here as observed facts. We can't do much about (1) but we can about (2) to (4) of course. It seems as if the body can process only a certain volume of each nutrient (energy, protein, vitamin, mineral) during a lifetime. Thus the more of those we ingest, the faster aging proceeds. On fasting days, however, our "allowance" seems to be added to again.

André

Makes sense.