Think your sitting posture is pretty good? Here’s a fun exercise: Ask a friend at work to snap a pic of you at your desk when you least expect it, suggests Stacey Pierce-Talsma, chair of osteopathic manipulative medicine at Touro University California. Are your shoulders more rounded than you realize? Does your head jut forward toward the computer screen? Are your legs crossed or twisted around the chair leg?

“Sitting might seem like a no-brainer, but you could be putting strain and pressure on parts of the body that weren’t meant to support that position for long,” Pierce-Talsma says. Over time, that extra strain can lead to tension headaches, neck stiffness, and back, shoulder, and elbow pain—for starters. In other words: Slouchers, it’s high time you set your alignment straight.

Before you spend another day in front of your computer, read these posture-perfecting tips.

1. Look level

Laptops are great for firing off emails and working on a presentation wherever you may be—a conference room, the airport, or Starbucks. They’re much less great for your body. That’s because when your head is tilted forward or down (a motion doctors call cervical flexion), it puts downward pressure on your spine. And with every degree, the pressure increases, according to a study in Surgical Technology International. At a 60-degree incline (let’s call this “thoroughly engrossed in my texting convo” height), the weight of your head feels five to six times heavier than usual.

“To avoid that extra pressure, you want your neck to be in neutral alignment,” says Pierce-Talsma, which means your monitor should be eye level. With a laptop, a stand that raises the screen can do the trick. For a desktop, prop the monitor on a few stacked books. And if you find that you tend to lean toward your screen, shimmy it a few inches closer to the edge of your desk.

2. Take a seat

You might not have had much say in your office chair, but if you’re able to request an upgrade, there are a few ergonomic features that will spare you some backache. Make sure your seat is height-adjustable, has armrests for when you’re not typing, and provides lumbar support (if it doesn’t, you can buy a seat-back cushion and place it where your lower back curves inward).

Or ditch your traditional chair for a bouncy ball seat. “I have a bouncy ball chair and I’ve noticed my posture is better and I have less discomfort in my low back,” says Pierce-Talsma. Because you engage your abs in order to stay balanced, consider making the transition over a few days or alternating between the two options to build core strength and lessen soreness. (And in case you were curious: The jury’s still out on whether a standing desk is the cure-all for sitting-related health woes.)

3. Find your height

Your chair should be low enough that your feet are planted comfortably on the floor and your knees are level with or slightly lower than your hips, says Pierce-Talsma. If not, you risk taxing large muscle groups and restricting blood flow to your lower extremities. Crossing your legs won’t immediately kick-start a backache, but “it’s definitely better to have both feet on the ground,” she says.

4. Set a timer

Sure, you know you should be taking short standing breaks throughout the day to increase blood flow and stretch your muscles. But how often do you follow through on that goal? For Pierce-Talsma, a timer helped turn a good intention into a good habit. “I set it for every hour,” she says, “and sometimes my break is a walk to the copier or to get a glass of water, sometimes it’s just 30 seconds of stretching near my desk.” She’ll often bust out the yoga pose warrior I, which stretches many of the muscles most aggravated and tightened during a long sit sesh.

Want to get your body moving more than just once an hour? Here’s what happened when an editor tried an at-desk elliptical for a week. And here are 10 ways to de-stress right at your seat.