If you work at a desk, the chair is one of the more important pieces of equipment you physically interface with. Get a good one. But, most crucially – get one that’s comfortable. You will not use an uncomfortable chair correctly no matter how good it’s supposed to be for your back!
Many chairs promise to fix your problems for you, with things like lumbar or head support. You may need those things! But if you find yourself struggling to get comfortable in spite of the additional features, it might not be the chair, but an issue in how you’re trying to sit. Your desired chair features should line up with your desired sitting position, and then you should also make an effort to sit correctly.
For example: if you’re the type that crosses your legs when you sit, you may find that sometimes your foot goes numb if left in that position for too long. That’s not the chair! Similarly, sitting on your shin can cause knee and leg pain over time, but on such a delay it can be hard to identify that as the cause. Leaning too heavily on one elbow can do the same, and all of these may cause one-sided back pain.
After the chair, the most important thing is to remember your posture!
There’s no easy way around it – you have to remember to sit correctly. Even tools designed to help you do that might not do the trick alone. The yoga ball chair seems like a good idea, but the truth is, they’re exhausting, and similarly easy to fall into bad posture habits with, albeit different ones than a conventional chair. You may find engaging your core to sit is annoying, and moving the chair is annoying too, leaving you to stand and lean over desks or slouch.
In truth, there aren’t many pieces of equipment that can fix posture passively, without negative side effects. Many of the harnesses designed to make you stand up straighter actually weaken the key muscles necessary for good posture, for example! It makes it harder to maintain that correct posture when out of the tool. For another example, Nike was forced to pay out about 40 million dollars after it’s Shape Up Shoe failed to deliver on promises of ‘toning muscle’ without needing the gym: it was supposed to exercise your legs as you walked by putting extra strain on your calves. Anecdotally, it was also unusually easy to twist one’s ankle while walking in them, which surely didn’t help.
Good posture is not something you can buy. Assuming no disability, the tools are not useful. It’s something that must be done actively. There’s no real easy way or cheat out of training into good posture.
Sources: https://www.ftc.gov/news-events/news/press-releases/2012/05/skechers-will-pay-40-million-settle-ftc-charges-it-deceived-consumers-ads-toning-shoes
