What factor is cited as the single most controllable influence owners can utilize to push longevity toward the higher end of the range?

Answer

Keeping them lean

Keeping the dog lean is described as perhaps the single most controllable factor owners can influence to push their dog toward the higher end of the estimated 8 to 12-year range.

What factor is cited as the single most controllable influence owners can utilize to push longevity toward the higher end of the range?
DogLongevitybreedNewfoundlandgolden