Taiwanese researchers have found that those people who did an average of 92 minutes per week of moderately intense healthy exercise lived on average 3 years longer than those who did not. This breaks down to about 15 minutes per day, and for most people they can get this amount of exercise from doing some typical household chores. However, the survey has been criticized for a lack of dependability on one of its protocols, which based the results on self assessments of exercise activity.
The survey was broad as it included responses from over 400,000 people over an 8 year period. However, it failed to factor in other important variables like diet, preexisting conditions or stress. This make it hard to argue that exercise was the causal factor behind the increase in life expectancy although it is certainly a possibility.