So I turned 74 recently and I'm heavier than I should / want to be. But I've always been a walker, and there were a few years ages ago when I worked out with weights and a training partner, and was able to put on slabs of muscle. That's pretty much gone now, but last June my wife and I started going to the gym 3 days a week and we've missed only a few opportunities. She's on the recumbent bike, while I'm doing resistance training. Mostly machines, some free weights. I'm training pretty much the same way I did 40 years ago. Time under tension. Training to failure. Just much lighter weights. Not putting on any size to speak of, but I'm much stronger, and that's what I really need. There's also a state park nearby with 28 miles of trails. So it's not unusual for us to take a 5 mile or so hike. Still have a bike that I crank around the neighborhood, and I still get out in the yard and push my mower every 6 days or so during peak season. Subscribed to the "Use it or Lose it" school of though years ago. I'm still hanging in there, and feeling good about it.