As nuduke has pointed out, decreased infant and child mortality may have had more effect on longevity than anything else. It used to be not that unusual, when families were really large, that the last child born would not survive for very long. It occurs to me that not having a lot of children might have made a difference, too. Certain ailments seem to run in families, too, which you can't do anything about. Basic sanitation, which is assumed today, and just getting enough to eat, also assumed today, probably make more difference than anything.
People also persist in habits that have been known to be unhealthy for ages, like using tobacco. I've never smoked but apparently people get something out of it. Likewise, certain occupations are also known to be unhealthy but I suppose they pay well, like coal mining. Something I think we forget and now take for granted is clean air and even, believe it or not, clean water. Originally, cities were unhealthy places to live, not because they were crowded, which they were, but because they were unsanitary and polluted. That was the original impetus for naturism, of which nudism was only one approach. The basic idea was to get out of town, into the countryside for hiking, exercise in the open air, with an element of conservation thrown in for good measure (hopefully not near a pig farm). For an urban worker to actually manage to get a vacation to be able to leave town for a week or two was an achievement in itself. So, it goes without saying that naturism, especially nudism, was a product of progressive (very progressive) thinking, as well as being largely urban. Presumably rural folks already enjoyed plenty of exercise in the open air (hopefully not near a pig farm) but were probably much too conservative to embrace nudism and too tired or busy to go hiking.