I have honed my exercise routine over the last few years to best reflect what best fits my outdoor needs. I have a huge advantage though because I live at the base of the mountains. I quit running because it hurt my knees and I don't feel it really helped me in the mountains. I have a hill behind my house that I can climb 2200' in 2 miles. That gives me more of a cardio workout that running ever could. I hike for 5 miles with a 30 lb pack 2 times a week, hike for 3 miles without a pack once a week (going for speed), lift weights once a week for my upper body, and every day I walk 30 min on my lunch, and 30 min in the evening with the dogs on the days I am not hiking.
One thing to note, diet is king when it comes to fitness. Diet will get the extra lbs off, not hiking with weight. If you show up out here for a hunt and have an extra 20lbs around your mid section, your recovery time will be greater, and your exhaustion will set in sooner. In all honesty, I have a buddy that comes out every year to hunt from sea level and all he does is diet his way to a healthy weight and does house chores. He does everything I can do without any problems.