I don't know how many times a day I tell my kids to sit properly on their chairs. Both cheeks! They just can't do it. They're up and down, kneeling, squatting, hanging off the side of that thing. Then we grow up and we get really good at sitting still. Sometimes for hours at a time! Barely moving. But here's the thing - when was the last time a kid told you their back was sore?
It is very very hard on our bodies to sit still for long periods. A lot of my yoga students have told me they are suffering with more back pain lately. Working from home, sitting on whatever chair is available at a makeshift desk is part of the reason.
So the first thing I would say is free your inner kid. Move. Regular movement breaks are an absolute must, even if that is to get up and have a glass of water! Better again if you can do a little yoga stretch - perhaps little bit of cat and cow, a little twist, a standing forward bend? You know the movements. Just do them slowly, mindfully. Drink your breath just like you do on your yoga mat.
The second thing is to adjust your posture so that you can sit with your spine in its natural curves. You want to sit up on your sit-bones. That means your pelvis needs to tilt forwards. This will allow your lower back to naturally curve inwards. To do this, sit towards the front of your chair. Make sure your knees are lower than your hips. I don't believe you need an expensive ergonomically-designed chair for this. There are cheap, simple things out there that really help.
An exercise ball is fab. It creates that forward tilt in your pelvis but it also encourages you to move. You'll find yourself rocking and rolling on it and that in itself eases out your hips and back.
Another simple, smaller option is an inflatable disc that you put on any seat so that it becomes curved, like the top of an exercise ball. Here's a link to one but you'll find loads on the internet. I used to use this when I worked in an office full time. The whoopee cushion my boss called it. I believe I bought him one in the end. https://www.mcsport.ie/p/-ufe-13-stability-cushion---pump-included/ufa257?gclid=CjwKCAjw7-P1BRA2EiwAXoPWA2oNdbpFuoTHZ0evhZbvPnhVM3R2w5hwXqrjfqTbSv7uQMggI7acchoChAIQAvD_BwE
A kneeling chair uses the same idea. See the picture below. Your knees are lower than your hips. Your pelvis is tilted forward so your lower back can curve in.
The upper back is naturally curved outwards and the neck curves in. But if you sit with your head reaching forwards, you lose that curve in the neck and your upper back will be stretched. This can lead to upper back and shoulder pain by the end of the day. To alleviate this, make sure your computer is at the right height for your eye-line and your arms can rest on a support. Be conscious of keeping your head aligned. Think about the soft palate of your mouth aligning with the centreline of the body, so the crown of the head extends up. You should be able to easily swallow. Imagine you were balancing a book on your head.
Finally factor in yoga! It will help ease out the tension that inevitably builds up and also build the core strength necessary to maintain that good posture.
If you've been struggling with back, neck and shoulder pain, I hope this helps. Please feel free to get in touch if you have any questions or you'd like any advice.