A new study in the journal The Lancet shows just how big of a toll physical inactivity takes on our health -- and how its relationship with death may be comparable to that of smoking.
Researchers from Brigham and Women's Hospital and Harvard Medical School found that not engaging in moderate exercise for 150 minutes a week (what is recommended by the Centers for Disease Control and Prevention) was linked with 5.3 million deaths worldwide in 2008 -- about 9 percent of all deaths.
"With elimination of physical inactivity, life expectancy of the world's population might be expected to increase by 0.68 years," researchers wrote in the study. "These findings make inactivity similar to the established risk factors of smoking and obesity."
(Researchers noted that that additional 0.68 years seems low because that figure was calculated taking into consideration both active and inactive people.)
The researchers analyzed past studies on the effects exercise has on the risk of different diseases. They found that not engaging in the recommended exercise levels was the main cause of 6 to 10 percent of coronary heart disease, breast cancer, colon cancer and Type 2 diabetes cases around the world.
Specifically, not meeting the recommended exercise levels was linked with 6 percent of coronary heart disease cases, 7 percent of cases of Type 2 diabetes, and 10 percent of cases of colon and breast cancer.
The CDC recommends that adults get at least 150 minutes per week of a moderate aerobic exercise -- like walking briskly -- plus two or more days of muscle-strengthening activities. Or, another recommended combination is 75 minutes per week of vigorous aerobic exercise -- like running -- along with two or more days of muscle-strengthening activities. Yet another recommended combination is doing a mix of vigorous and moderate aerobic exercises along with the two days or more of muscle-strengthening exercise.
And you don't need to do all that exercise in one sitting: The CDC says that doing just a bit at a time -- even 10 minute increments -- can help you achieve recommended exercise levels.
For some exercises that have been linked to living a longer life, click through the slideshow: