People who had a record of sustained and regular exercise -- meaning vigorous activity at least once a week -- boosted the likelihood of "healthy ageing" sevenfold compared to a lifestyle of persistent inactivity.
The gain among newcomers to exercise was roughly triple.
"Significant health benefits were... seen among participants who became physically active relatively late in life," the paper said.
"Healthy ageing" was rated by an absence of major diseases and disabilities, good mental health -- the lack of depression or cognitive decline -- and the ability to maintain social connections.
Around a fifth of the volunteers fell into this category at the eight-year followup mark.