By now we're sure you know that sitting all day isn't doing your health any favors.

Spending too much time seated at a desk has been linked to all sorts of negative health effects, like an increased risk of diabetes, cancer and, yes, even death.

"We've been trying to tell people this for a long time," Noam Sadovnik, D.C., a chiropractor and founder and director of chiropractic and physical rehabilitation at The Center in New York City tells The Huffington Post. "We're just really not designed to sit for prolonged periods of time."

Regular exercise and periodic standing breaks throughout the day are certainly good ideas. Not to mention there are all sorts of quick-and-easy exercises you can do at your desk, plus sneaky ways to incorporate more movement into your day, like taking the stairs and holding walking meetings.

But stepping away is easier said than done, with ringing phones, tight deadlines and meeting after meeting after meeting. When you're stuck sitting, how you sit in your chair can be just as important as how long you sit, especially if you find yourself in pain by the time you head home.

Experts agree that keeping the joints at 90-degree angles is one of the most important tenets of perfect desk posture. We asked Sadovnik to elaborate, so he offered the following head-to-toe tips to make sure your workstations are as supportive as possible.

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  • Head And Neck

    "Eyes should be about level with the top of the computer screen or the top third of the monitor," says Sadovnik. They'll drift down naturally when you need to glance at the bottom of the screen without straining your neck, he says. <br><br> It's also important that you face the screen straight on. Sadovnik says that workers with two monitors are likely to twist the upper body to view the second screen. "Moving the shoulders relative to the hips can create stress," he says.

  • Arms And Elbows

    Leaning on an arm rest can help keep you from slouching, but could also cause you to painfully scrunch up your shoulders. "Think of a suspension bridge," says Sadovnik. "You want every joint to hang gracefully." <br><br> Arm rests should be positioned at a height where you can comfortably keep your shoulders back and down, while still being able to reach the keyboard or mouse without stretching. (Note: Repeatedly reaching for the keyboard or mouse can create stress and pain all of its own!) <br><br> Elbows should also ideally be at 90 degrees, so your <a href="" target="_hplink">forearms are roughly parallel to the floor</a>, according to the Occupational Safety & Health Administation (OHSA).

  • Lower Back

    Many newer office chairs are designed with lower-back support built in, but if yours isn't, simply placing a pillow or a support tool called the <a href="" target="_hplink">McKenzie Roll</a> at the small of your back can help, says Sadovnik. The idea is to maintain the natural, <a href="" target="_hplink">reverse-C shaped curve</a> in the lower back. Over-flexion contributes to many of the cases Sadovnik sees at his chiropractic practice, he says.

  • Legs

    If your knees are <em>higher</em> than your hips, your chair is probably too low, explains Sadovnik, while knees that are much <em>lower</em> than the hips mean your chair is probably too high. Ideally, your knees will be just slightly lower than your hips, allowing your <a href="" target="_hplink">thighs to be parallel to the ground</a> and your lower legs perpendicular, according to OSHA.

  • Feet

    Both feet should be <a href="" target="_hplink">firmly planted on the ground</a>, according to OSHA, so that the ankle joint can also be at 90 degrees. <br><br> If you find your feet dangling off the floor, gravity may be pulling your back out of its natural curve. Sadovnik recommends using a foot rest, whether it's a <a href="" target="_hplink">store-bought wedge</a> or simply an empty shoe box.

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