So far all excellent advice, especially the sprints and getting acclimated early. I would like to add kettlebell swings as an incredible builder of all things climbing. They are simple to exacute but difficult to explain. Google kettlebell swings and several video demos will come up. Done correctly they build both musculature and flexability in the hips, glutes, lower back and abs. That's all great but the real kicker for you is that the deep breathing/coordinated breathing is very aerobic and you are killing two birds with one....arrow. Other simple exercises of great benefit,run the stairs, varying number of steps you take with each stride, add pack when your footwork is good. One last easy to work on exercise, deep breathing. While driving, watching tv, whatever, fill your lungs, hold for one count, exhale completely,repeat. This is phenomenal for overall health and peace of mind but treat your lungs like a muscle and exercise them often and you won't be surprised buy the difficulties of elevation. Like exercise to help shooting your bow, this stuff will help but therre is nothing like being at elevation to get used to it. Good luck, stay hydrated, happy hunting.