You may have recently started to work from home, without the time or the knowledge to adapt properly and without the opportunity to set up a comfortable workstation. If your working conditions aren’t adequate, it can lead to the onset of adverse health conditions such as a bad back, wrist ache, neck strain and so on.
If you find you are sitting in a kitchen or dining room chair, these were never designed for sitting in for long periods of time. If your homeworking is ongoing, can you arrange for your office chair to be delivered to your home?
Likewise laptops aren’t always suitable for long periods of use if they are not positioned correctly.
Despite limitations, you should do your best to achieve a good posture wherever you are working, even if you are doing so temporarily.