As far as work outs go you'll get a bunch of replies all with different thoughts. For me personally I avoid steady state cardio (jogging), jogging sucks and it's boring.. I do a lot of interval training 2 to 3 months ahead of the season. These consist of hill sprints, farmer walks, tire rolls, and sled pulls. Interval training is basically go all out of 10 to 30 seconds, taking a 30 second to 1 minute rest and doing it all over again. My main focus on theses is to get the heart rate up and metabolism pumping. Ever wonder why long distance runners are usually small and sprinters are usually more muscular, interval training is a large part of this. Elk hunting takes as much strength as it takes cardio endurance.
As far as diet try the paleo (caveman) diet . If you can't kill it, pick it, or grow it don't eat it that simple.