Best advice for you! I also come from Illinois and make the trek to Colorado and hunt public ground DIY elk every year. Coming from 400-600 ft. elevation and hunting from 7000'-11,000' is going to traumatize your body. Do as much running, weightlifting as possible. Climb some hills if you have any around. Try to get the thighs working as hard as possible. It could make or break your hunt. Elk hunting in the rockies is a fantastic experience you won't soon forget, but if not donewith some forthoughtyou could regret it! Good luck!