Sitting
It is best to sit in an upright chair that supports your lower back. To find the correct sitting position from a forward slump, throw the head well back and bend it forward to pull in the chin. This will straighten the back. Now tighten the abdominal muscles to raise the chest. Your head should be line with the spine. Check your position regularly.
Workplace Ergonomics
A desk and chair should be of sufficient height
And with enough leg room so you can get close enough to sit up straight and work comfortably. To take the pressure off your back, keep your thighs parallel to the floor and keep your feet flat. Crossing your legs is a no-no; you are actually twisting your back in order to keep legs crossed.
Standing
According to some physiotherapists, in a fully erect posture, a line dropped from the ear should go through the tip of the shoulder, middle portion of the hip, back of the knee and front of the ankle bone. To find the correct standing position, stand one foot away from the wall. Sit against the wall, bending knees slightly. This will help tilt the pelvis back and flatten the lower spine. Holding this position, inch up the wall to standing position by straightening the legs. Now walk around the room maintaining this position. Then place your back against the wall again to see if you have held it.
Lifting
Always turn to face the object you are lifting, even if it's just a piece of paper. The right way to lift is with your elbows near your body. Get a firm grip with the palms of your hands and the roots of your fingers and thumbs rather than with your fingers alone. Bend at your hips and knees, not your waist so your thighs carry the loads instead of the back, and keeping the back straight, raise yourself with your legs.
Sleeping
When you sleep face down, it exaggerates arching of the lower back and can also strain the neck and shoulders. A proper sleep posture holds your spine in its natural “S” shape. So go with the fetal position - on your side with knees slightly bent, effectively flattening the back. A pillow between the knees helps increase comfort, place a pillow under your knees for support.
