We bought a desk-desk and a chair for the son of a first-grader precisely in order to help him in correcting his already developed scoliosis. Since December, he has been studying only for her. And standing and sitting, according to the mood. So, now we are visiting grandfather and grandmother, our favorite desk is not here. But here's what I noticed when my son was sitting at an ordinary flat table and writing in a notebook.
Perfectly flat posture !!! He felt so comfortable !!! I am delighted! The desk helped him find the right posture and fix in the muscle memory the right posture in which the spine feels good !!!
Strengthen the muscle corset: physical exercises for all muscles of the back and abs, yoga, swimming. The gym helped me the most. You need to exercise regularly and taking into account your stamina and health.
Stretch, particularly hang from a bar.
Constantly monitor the position of the back. You can ask others to remind you of this, or you can buy a posture brace (or something like that) - a thing that vibrates if you break the correct position.
From time to time, briefly wear a simple corset (sold in orthopedic stores). Perform this exercise: approach the wall, aligning the back of your head, back, butt and heels along it, then step back and go about your business, remembering the position.
In order not to slouch, you need to swing your back, and in addition, it is better to swing your abs - this way a muscle corset will appear that will help keep your back straight.
I strongly advise you to contact a surgeon. The doctor will look at the state of your posture, give directions for exercise therapy, massages, or give a list of home exercises that you will need to do yourself. But in general, it is good to periodically control yourself when you are standing, sitting, going somewhere. Make sure that your back is straight during these moments. Over time, you risk getting used to.