^^Nailed it^^Best of luck!
Like mentioned, try to plan for the elevation, especially if your new to it. Acclimate a couple days before, driving out seems to work great for me. Stay hydrated and make sure you eat your minimum calories. Don't kill yourself the first couple days either by trying to go too deep.
I lived in Colorado for a few years. The altitude is no joke. It'll sneak up on you quicker than you think. Great advice AT Hiker. Hydrate, hydrate, hydrate....like set an alarm on your watch or something. You'll get caught up in the beauty of CO and the moment and forget.
"Relatively good shape" isn't good enough for Colorado elk hunting, sorry to say. Push yourself at elevation (training) so you don't kill yourself at altitude.
Gun, be comfortable and accurate out to 800 yds. It's big country out there.
Man, that's exciting! Congrats and I hope it's a trip of a lifetime, elk or no elk. Can't wait to see the pics.