First and foremost, don’t sit for too long. You can get very expensive chairs, but if you sit on them for lengthy periods of time, you are still going to get aches and pains. Take regular breaks – at least five minutes every hour – and have standing or walking meetings. Walk to talk to somebody instead of sending them an email.
If you are working from home, a hard kitchen chair is probably not as good as an office chair, so take more breaks. Relaxing in an armchair or on the sofa will have less of a toll on the body but you will still need toget up frequently. Movement is the key to good muscular-skeletal health.