Ask HN: What are you doing to look after your posture?

I guess we all know what sitting in a chair looking at a screen all day can do to you. Forward head posture, rounded shoulders, tight chest muscles, back and neck pain.

What do you do to look after your back and neck?

EDIT: As an aside to this, does your employer offer any help in optimising your work setup for posture? Is it reasonable to expect this?