In the Lancet online, they suggest that 15 minutes of physical activity per day can reduce a person's risk of death by 14% and increase life expectancy by three years compared with inactive people.Expect new adverts from gyms - join our gym and you could become immortal!
Of course, somewhere a time-frame is missing. Presumably the 14% reduction is within a given time frame. The abstract of the article doesn't mention a time-frame. Definitely something wrong here though.