A lot of us have years of baseline miles put in. I'm almost 72 and have been riding for 15-20 years and I'm sure many of you have ridden longer and more intensely. I don't go out unless I can get at least 20 miles in. For a few reasons, big one being susceptible to svt's, I don't ride too hard. That might change, fingers crossed. I'm focusing on other exercise for now, but try to ride 3 days a week. For me, 25 miles keeping heart rate in zone 2-3 is kind of easy even if I've not ridden for a bit. I don't consider it hard and and do it more to get outside on a nice day than for exercise. It's more like slow walking. Doing the same ride intensely at high HR is real exercise, even training. Just saying that if you've been doing it for a while you can almost always do a gentle 25 miles or so. The numbers you posted are not surprising to me.