Gosh. I'm 68 and recently hiked over a hundred miles in the high country with a 65 lb pack - which would have been my definition of "ultralight" a decade or two ago. Desert canyon hiking was way heavier, or adding real mountaineering gear. Day hikes can obviously be much lighter. But in the mtns you always want a rain parka and light coat or sweater along too, and not just photo gear, or you risk becoming a statistic. Conditioning takes commitment. Get a good pack and gradually build up the weight until your back and shoulder muscles are accustomed, and you gain stamina. But it sure beats running on treadmill in a stinky gym, like a hamster in a cage.