This from BBC Health:

Regular exercise in old age has as powerful an effect on life expectancy as giving up smoking, researchers say.

The analysis of 5,700 elderly men in Norway showed those doing three hours of exercise a week lived around five years longer than the sedentary.

The authors, writing in the British Journal of Sports Medicine, called for campaigns to encourage fitness in older people.

The study comes as a charity warns about low levels of exercise.
In the study – conducted by Oslo University Hospital – found both light and vigorous exercise extended life expectancy.

Full BBC Health Article: Elderly people who exercise ‘live five years longer’ – BBC Health