to add to what
@180ls1 said
Here is a simple nutrition plan: read the ingredients labels on packaged food and don't eat anything with any form of sugar (anything that ends in "...ose" like dextrose, glucose, etc.).
https://www.virtahealth.com/blog/names-for-sugar
Assuming you have a freezer full of organic, wild caught, free range, grass fed...meat that you harvested in one manner, stick to the fresh (unpackaged, unprocessed) foods isle of the grocery store.
If you are time constrained during the work week, get out for a walk around the neighborhood before and/or after work for 30-60 minutes at a pace of at least 3 mph. Wear ankle waits to simulate boots and a backpack full of gallon jugs to your desired pack weight (~40-60 lbs). Do another walk during lunch time at a similar pace using similar equipment. You can cover 4-9 miles per day. This will help improve your fitness on the mtn. You will still suck wind, but you will suck less.
Park at the back of the lot at the store, carry items (groceries, etc.) in hand rather than in a cart.
Take the stairs instead of the elevator.
Lots of little things can add up, the science backs this approach. Anything to get your heart rate elevated and your raspatory rate up will make your body more efficient at processing oxygen, which will translate to the mtn. Do it consistent at least 60 minutes per day.
Practice like you play. On the weekends, hike/run up mountains or do whatever you do during the hunting season.
If you can find a workout/nutrition buddy to help keep you on track and motivated, that will help too.