I'm curious what people do to keep in shape for strenuous backkpacking when they can only go a few times each year. I moved to Dallas, TX (300 feet) but backpack in the Colorado Rockies (trail head 8-9000 feet - and pack up to 9-10 miles a day to 12-14000 feet) We may gain 2-3000 in a day.

I regularly lift weights in the gym so hauling my sub-30 pound pack is not a problem, and I do a breathing exercise so I don't get headaches, etc from altitude sickness.

But I get exhausted and think some kind of cardio training would be in order. Jogging and tread mill have been my solution in the past, but knee problems limit them now. The stair master and the elliptical machines seem possibilities, as does bicycling.

My next trip is just a month away, so I want to use my time wisely, but I also want to find something that can keep up with so I'll be ready next season. BTW I'm 62 years old, but have no intention of "acting my age".

Please share what you have found is most helpful to keep in shape?