Sitting for most people is an unavoidable part of life. However, it does not have to destroy our back.
What goes wrong?
Sitting applies slow creeping forces to the connective tissue of the lower back. This slow creeping force exerted on our lower back from sitting is similar to the one that is capable of moving teeth under a slow constant force of a dental brace. As we slowly slouch, the force of gravity travels through the spine in an abnormal way which over time damages the tissue. This damage happens slowly and most people become aware when things reach a breaking point and enough inflammation builds up. This can result in a herniated disc, a sprain in the ligaments of the sacroiliac joint, tight muscles, and arthritis in the joints.
How to avoid it?
Simple advice but can be a hard habit to break for some.
Don't work on a couch.
Sit up higher so that your knees are slightly below your hips.
When sitting, be sure to apply some of your weight onto your feet and sitting bones of the pelvis. It is important to distribute your weight among four points, both pelvic bones, and both feet. It will then be easier for the brain to recruit the right muscles and create a healthy elongated spine.
Learn to bend in your hips. See the video link here of how to practice the hip hinge exercise.
Have your screen or your book at eye level. Looking down all the time not only strains your neck but also your lower back.
Take breaks every 30 minutes, at least for a few seconds to reset your posture.