I think a fittness plan with a diet low in fat high in protien with as many fruits and vegtables as one can eat is best. 2000 calorie a day with less than 20 grms fat.Exercise would be running and weight lifting in an arobic style. A program for the mind as well to keep it fit which would involve plenty of reading. Also do what is possible to reduce as much unneeded stress. Mix that up with love of hunting and family with thankfulness to God and I figure a person would be able to hunt anyway they choose well into their 80's maybe slowing down in their 90's.
