Fill your pack up and put on lots of miles! Use any inclines you can find as well as uneven ground. I shot my first elk in great cardiovascular shape and still nearly quit during my pack out. This year I put nearly 150 miles on with 65 lbs on my back prior to going out and would have gladly packed out another one the same day.
Do WAY more then you think you need to, it will be worth it!
Do WAY more then you think you need to, it will be worth it!