Correcting a curved spine/poor posture

[Frimley111R]

Being born a petrolhead, part of my youth (early-mid teens) was spent with r/c cars and I spent many hours sitting on a stool in the garage, bent over working on my cars.

As a result I developed a curve in my spine or two to be exact. I'm now round shouldered and the lower part of my spine bends in more than it should.

I have no idea how to stop this or rectify it short of learing to lie flat on my back on the floor every night with a couple of books on top of me.

Any ideas?