I was in your situation about 8-9 years ago but a bit older. I'm also from Illinois and my goal was to do a full-on archery Elk backpack hunt, everything on my back for 8 days. My birthday is in September and I wanted to do it for my 50th birthday. We've been going about every other year since and I'm quickly approaching 60 now. My brother is my partner in crime - he is a couple years younger than me, but with 7 stints in his heart, lung issues and generally not in great shape. I can tell you all the things "NOT" to do for your first back country hunt. I too romanticized about how cool it would be to hike in away from the crowds and "rough it", but I can tell you, if you aren't prepared, it will kick your ass. Ask me how I know?
Thinking back on that first back pack trip, I wish we would have had a film crew following us. We could have made a fortune showing how two unprepared midwestern red necks fumbled & bumbled their way through a week of chasing Elk at 10,00 ft. It was a total Laurel and Hardy operation, but we actually got into elk and had some decent encounters, just couldn't seal the deal. That's what keeps us going back - plus being in the mountains in September is worth it whether you kill something or not.
So here is my list of things to think about for a 1st timer:
- Watch the weight of your pack. The saying "ounces = pounds, and pounds = pain" is no joke. My brother and I scoffed at all the hard core guys cutting down the handles of their toothbrush to save weight. You don't need to go to that extreme, but you need to watch weight wherever you can. My brother and I each got ALPS freighter packs off eBay and just crammed them full of everything we thought we would need. We never weighed them or did any real hiking with them. We got to the trail head and threw them on our back - that's when we knew we were in trouble. You literally could not get them on your back with out the assistance from the other guy. I'm guessing close to 90+ lbs, it was brutal.
- Get in shape. We talked a good game about getting ourselves in shape for the trip, but we weren't in any better shape than our normal day to day. We haven't been great at doing this on our trips since the first one either. Our usual MO is to come screeching into the parking area, throw our packs on and starting blazing down the trail at 7800' - heading up all the way. You wanna talk about sucking air. Elevation is 721' where I live - oh baby!
- Camp low - hunt high. The first trip, we hiked all our gear up to almost 10,000' where we found a spring for water. That about killed us. We now camp in the valley at about 8600' next to a small stream and hike higher each morning. At the end of the day, when you are beat and tired, its good to know you are going to have a relatively easy downhill walk back to camp. The first year we found ourselves in situations where we were almost at the bottom at the end of the day, and had an arduous hike back up to 10,000' in the dark - arrrgh!
I a few things got us through our first couple trips at our age:
- We are stubborn and won't quit once we are into something. My brothers one of the toughest guys I know. Even with all his ailments, he never complained once and kept on humping it, often out doing me.
In the first hour of our first trip we got off course and ended up in a swampy bog with beaver runs in it. My brother tried to hop across one of the runs and ended up waist deep in water. When he tried to push himself and the heavy pack up out of the muck he heard something pop. He tore his groin bad. He looked at me all pale with sweat beads forming on his head and said "sh..t I just messed something up bad" He was determined it was not going to end our dream trip in the first hour after driving for 24 hrs.
His thigh the next day. He kept going on this for a week:

- We are good hunters in general and are use to hunting large tracks of land in Northern Wisc. Not the same as the mountains, but being in deep in unknown terrain doesn't bother us. We have good woodsman ship skills and understand animals (farm kids).
We have learned a ton every trip, and things are getting easier each time, but now age is starting to catch up with me. I'll keep going as long as I can.