You will never forget it. I've been going for four years now and will return to Colorado to go until I physically cant hang. The cardio workout will help but you will still be sucking wind. Just be prepared for it. The best advice i can give you is to hunt this year and learn. The population of gun hunters is overwhelming. You will no doubt have parts of your hunt ruined by other hunters that walk up on you, scare Elk that you are watching and on and on. Like I said, hunt this year with a gun and learn. Next year buy a bow and avoid all the hassle of gun season. Remember, you gat a month to bow hunt, 4-5 days to gun hunt.
Scott