Alternatives to the traditional sitting desk, like this stand-up model from Anthro, are catching on.

Sitting. It seems as innocent and natural as breathing or sipping a cup of tea. And yet, some health experts warn that too much of it could be deadly. If you’re sitting down reading this, you may be standing up before it’s all over.

Most people understand the connection between obesity and poor health, and the importance of being physically active every day. But public health guidelines rarely mention the importance of reducing sitting time—even if you’re active—and they probably should.

A 2006 study led by Alpa Patel, Ph.D., of the American Cancer Society examined the correlation between sitting time and mortality, and the results are alarming:

“They found that more leisure time spent sitting was associated with higher risk of mortality, particularly in women,” reports Science Daily in a press release. “Women who reported more than six hours per day of sitting were 37 percent more likely to die during the time period studied than those who sat fewer than three hours a day. Men who sat more than six hours a day were 18 percent more likely to die than those who sat fewer than three hours per day. The association remained virtually unchanged after adjusting for physical activity level.”

The study, which can be found online in the American Journal of Epidemiology and has since been backed up by similar studies, monitored 123,216 individuals who had no history of cancer, heart attack, stroke or lung disease, for a period of nine years.

It’s worth noting that the increase in mortality found in Dr. Patel’s study was more strongly associated with cardiovascular diseases than with cancer.

“Several factors could explain the positive association between time spent sitting and higher all-cause death rates,” says Dr. Patel. “Prolonged time spent sitting, independent of physical activity, has been shown to have important metabolic consequences, and may influence things like triglycerides, high density lipoprotein, cholesterol, fasting plasma glucose, resting blood pressure and leptin, which are biomarkers of obesity and cardiovascular and other chronic diseases.”

Awareness about the dangers of sitting too much has been spreading, and the future of office furniture could be less cheek-oriented: Forbes recently reported that Ergo Desktop saw a tripling of last year’s sales of an attachment that converts a conventional sit-down desk to a standing one.

So when five brand-new, stand-up desks were rolled into Cruzioworks, a downtown co-working space where I do a lot of my sitting, I jumped on the opportunity to try them out.

The secret, I realized, is finding a balance. Sure, standing does burn more calories than sitting, but constant standing has its own health risks attached to it, including varicose veins, circulation problems and swelling feet, according to one 2005 study of workers in the United Kingdom who stand all day.

Slumping at a desk for eight hours is just as extreme as being firmly planted on an assembly line. And while treadmill stand-up desks (now appearing at Google and Facebook) may seem like a rash step for the chair-bound worker, stirring a stagnant workday with movement should not. Going out for walks, sitting on a yoga ball, or even placing hula hoops in the break room aren't bad ideas. And neither is experimenting with the standup desk. Just remember to take it slow.

By the end of the day, my feet throbbed, and all I wanted to do was sit down, even if it meant dying three years sooner.