Even though the elk hate me and always disappear when it is hunting season, I try to stay in shape year round. At my age, it is easy to get out of shape and tougher to get back into shape. I hike 6 or 7 miles 5 or 6 days a week, mountain bike, and lift weights (lighter weights, higher reps), so for an old fart I can still hike the mountains. It is a bonus to now spend a few months in Arizona during the winter; the hiking and mountain biking where we are is fantastic, and the rugged country makes for some sweaty workouts.
Keep up the good work, and you will find the mountains a little less steep come September.