More than 40 percent of working people are sitting at a desk from 9-5, and researchers have calculated that this prolonged sedentary behavior contributed to some 433,000 deaths a year from 2002 through 2011.

If you're not taking a break every half-hour, then it might be time to do so. In fact, making this one change in your daily routine could reduce your risk of death, according to a new study published in the Annals of Internal Medicine.

Even for people who go to the gym, sitting for excessive amounts of time — in a single stretch has a greater risk of early death, the study showed. Not to mention the long list of health problems and illnesses that are related to sedentary behavior.

"This study adds to the growing literature on how dangerous long periods of sitting are for our health, and underscores a growing awareness among clinicians and researchers that sitting really is the new smoking," said study co-author Monika Safford, M.D.

Though previous studies have linked sedentary behavior to early risk of death, none has reported on how much time individuals should actually be active for, thus hindering the relationship between risk of death and inactivity. The results of this new study showed that sitting around accounted for 77 percent of the total waking hours for the average individual, meaning that more than 12 hours a day are being spent inactive.

"The lack of activity in our muscles affects our ability to metabolize our sugars efficiently," Dr. David Alter told Reuters. "Over time, our body accumulates excess fat, which can lead to obesity, diabetes, heart disease, cancer and death."

According to the Centers for Disease Control and Prevention (CDC), adults need at least one of the following options for physical activity:

  • 2 hours and 30 minutes of moderate-intensity aerobic activity (brisk walking) every week and muscle-strengthening activities on two or more days a week that work all major muscle groups including legs, hips, back, abdomen, chest, shoulders and arms.
  • 1 hour and 15 minutes of vigorous-intensity aerobic activity (jogging, running) every week and muscle-strengthening activities on two or more days a week that work all major muscle groups including legs, hips, back, abdomen, chest, shoulders and arms.
  • An equivalent mix of moderate- and vigorous-intensity aerobic activity and muscle-strengthening activities on two or more days a week that work all major muscle groups including legs, hips, back, abdomen, chest, shoulders and arms.

The CDC notes that 150 minutes may seem like a lot, but the exercise doesn't have to be all at one time. As long as you're doing physical activity, just 10 minutes at a time will suffice.

"Per national physical activity guidelines, clinicians should continue to encourage patients with obesity to participate in moderate-to-vigorous intensity physical activity for at least 150 minutes/week to improve their cardiovascular and metabolic health," Wendy C. King, PhD, told Endocrine Today.

"It only makes sense that those short-term changes translate over time to more profound changes in the risk for diseases linked to sedentary behavior," Dr. James A. Levine told the Los Angeles Times.