I was 73 April 4, 2016. I'm in pretty good shape for a man of 53 according to my doctor. No heart problems (complete cardio-vascular workup in 2014 with outstanding results) and no knee problems. So I think I have another 10 years of backpacking in me - but maybe not backpack hunting with the extra weight of a scoped rifle and butchering gear. I live in the Las Vegas valley and in summer I have to work out on our treadmill set at max angle and with 4x6 blocks under it. I put on heavier work boots and a 35 lb. pack, turn on the TV to Star Trek and do an hour at 2.2 miles an hour. Starting in September I will go into our nearby Spring Mountains twice a week with the same pack and hike at 8,000 to 10,000 ft. to check my ability to hunt those altitudes in northern Nevada this October. In my 30s and 40s I cross country ski raced and bike raced in the summer in western Pennsylvania so I have a competitive athletic background and know how to train. BUT, since i hunt alone I carry a SPOT satellite locator beacon with me to call for help so the coyotes won't gnaw on my carcass if I have a big accident. I recommend it to all hunters because we are not always with friends during the day. Jus' saying'... Eric B.