Proper body posture at work

From the link: http://www.canadianbusiness.com/article/20459--how-to-deal-with-that-pain-in-your-133

Perfect your posture

• EYES Eyes naturally angle down 15 degrees, so your eye level should be at the point where the computer screen and its frame meet. If you wear progressive lenses, however, lower your monitor to avoiding tilting your head back to see top of the screen.
• BACK Most people try to sit straight by perching on the edges of their chairs, but end up curving their backs within 20 minutes. Don't do that. Your chair should have built-in support for the curve in your lower back so you can sit up straight. If it doesn't, purchase a lumbar support cushion.
• ELBOWS Adjust your armrests vertically and horizontally so your elbows are supported at a 90-degree angle and shoulders can relax. If your desk is too high for that, attach a keyboard holder under your desk.
• WRISTS Your wrists should be straight and supported by some padding on the desk or keyboard holder. Keep your mouse and keyboard close enough so you can reach them while maintaining a neutral position.
• HIPS & KNEES Your hips and knees should be at a slightly larger than 90-degree angle to avoid disc compression. Either adjust your seat to a downward tilt so your knees are lower than your hips, or recline your chair backwards so your knees move lower than your hips.
• FEET If your feet don't touch the floor, support them with a footrest, but one low enough that your knees bend at a 90-degree angle. 
• Stretching exercise for you, love... :)
• NECK Raise your left arm and place hand at base of neck so the elbow sticks up like you're about to do a biceps curl. Twist your neck to look over your right shoulder. Hold for 30 seconds. Repeat on the other arm.
• WRISTS Hold your right arm straight out in front with fingers facing upward. Pull back the fingers with your left hand. Hold for 30 second. Flip your right hand down and use your left hand to press on the back of the right.
• HAMSTRINGS While standing, put your right foot a couple of inches in front of your left. Bend your left knee and rest both hands on the right thigh. Hold for 30 seconds. Repeat on other side.
• SHOULDERS Bend both arms at 90-degree angles with palms facing one another. Bring your right arm over your left so your right elbow crosses over the left. Touch your right palm with your left-hand fingertips. Move your elbows in small circles, to the right, then to the left. Repeat on other side.
• LOWER BACK Stand up and curve your back like a cat. Bend down to touch your toes. Hold for 30 seconds. This will also stretch your hamstrings.