Posture is not about standing up straight on command. It is the position your body settles into by default — and that is the product of which muscles have become short and tight, and which have become long and weak.
Sitting for eight hours a day does predictable things: hip flexors shorten, glutes switch off, the upper back rounds, the neck pushes forward to compensate. Sport does its own version, usually asymmetric.
The approach
Assessment first — looking at standing posture, how you move, and which structures are restricted. Then hands-on work to release what has shortened, combined with specific exercises to strengthen what has lengthened and weakened.
Hands-on work alone will not hold. If the pattern that caused it is still there, the tightness returns within weeks. The exercises are the part that makes it last, which is why you get a plan rather than just a treatment.