Ran across this scientific nugget at SciTechDaily (also the image credit), where I learn all sorts of cool stuff:
The Glanville fritillary butterfly (Melitaea cinxia) was studied by researchers, who measured its metabolic rates. They found that whether the butterflies were lab-bound or released to island meadows in Finland, the ones who flew more energetically lived longer.
The obvious take-away is that the more we move, the more we live. Duh--a no-brainer for Ultrarunners, who already knew that.